1
•1
TM
loMy
TI-99/4A
Aubrey B. Jones, Jr.
IT AY DEN
I Speok BASIC
to My
TI-99/4A
I Speok DASIC
to My
T I -99/4 A
Aubrey B. Jones, Jr.
HAYDEN BOOK COMPANY INC.
Hasbrouck Heights, New Jersey
To Alyce, Aubrey III, and Adrienne
Production Editor: LORI WILLIAMS
Developmental Editor: KAREN PASTUZYN
Book Design: JOHN M-ROBLIN
Compositor: VAN GROUW COMPOSITION CO., INC.
Printed and bound by: COMMAND WEB OFFSET INC.
Library off Congress Cataloging in Publication Data
Jones, Aubrey B.
I speak BASIC to my TI-99/4A.
1. TI-99/4A (Computer)— Programming. 2. BASIC
(Computer program language) I. Title. II. Title: I speak
BASIC to my TI-99/4A.
QA76.8.T133J66 1984b 001.64'2 83-26674
ISBN 0-8104-6173-0
TI-99/4A is a trademark of Texas Instruments Incorporated, which is not
affiliated with Hayden Book Company, Inc.
Copyright © 1984 by HAYDEN BOOK COMPANY, INC. All rights reserved. No
part of this book may be reprinted, or reproduced, or utilized in any form or by
any electronic, mechanical, or other means, now known or hereafter invented,
including photocopying and recording, or in any information storage and retrieval
system, without permission in writing from the Publisher.
Printed in the United States of America
123456789 PRINTING
84 85 86 87 88 89 90 91 92 YEAR
Preface
Welcome to the world of computers. If you are a person who has recently bought a
computer or who has use of a computer, this book can help you. It was developed for
those who have little or no understanding of computers but who would like to learn more
about them.
The computer is a valuable tool that can solve problems, print words, draw pictures,
store information, play games, and do many other things. But it is important to understand
that a computer without the proper programs (instructions) is of very little value to you.
This book teaches you how to write programs in BASIC, a very simple, easy-to-use (and
learn) programming language.
Computers are found almost everywhere today — video games, appliances (microwave
oven control), autos (mileage computers), and cameras (automatic exposure). With the
cost of computers continuing to fall, especially the very small microcomputers, they will
soon become as ubiquitous as television sets. You see them at work, at the bank, and at
home. In the future, they will be as commonplace and as simple to use as telephones.
Because of the influence computers will have on our society, it is important that you
prepare yourself to meet the challenges of the future. I recognize that you might not want
to become a programmer, an engineer, or a systems analyst, but I feel that you should
become computer literate. To become computer literate, by my definition, means that you
understand the limitations of a computer. It means that you are not intimidated if you are
asked to use a computer. It means that you recognize that the computer is a tool, a very
powerful tool, that can help you become more productive and effective in our society.
This book will be just the beginning of a very exciting and rewarding experience with
computers for you. Even if you learn just a few of the fundamentals about computers and
learn how to write only very simple programs, you should remember this: You do not need
to know how to program a computer in order to use one! That is, you could purchase
programs written by someone else from most computer stores. But I feel that you will
have a better appreciation for the computer if you understand a little about how programs
are written and how the computer (together with its programs) provides you with the
desired results.
Finally, this book will get you started with computers, will eliminate the mystique of
computers, will help you build your self-confidence if you need it, and (best of all) will be a
lot of fun. After you complete this book, you will be able to say, "I speak BASIC."
Aubrey B. Jones, Jr.
CONTENTS
Part 1 Hardware (The Machines) 1
Objectives; Typical Data Processing Operation: Basic Parts
of a Computer; Box Diagrams of Computer and iVIicro-
computer Systems; Practice 1
Part 2 Software (The "Program") 13
Objectives; How Humans Talk to Computers; Machine
Language (Bit, Byte, KByte); A Program in BASIC;
TI-99/4A Keyboard; TI-99/4A Power-Up Rules; Practice 2
Part 3 Your First Computer Program 35
Objectives; Writing Your First Computer Program; Executing
Your Program; Correcting Common Errors; Key Words
(PRINT REM, END); Commands (CALL CLEAR, LIST,
NEW, RUN); Edit Mode; Practices 3, 4, 5
Part 4 More Programming Tools 61
Objectives; Math Operators; Order of Arithmetic Operations;
Variables; Key Word (LET); PRINT Zones; Use of Commas
and Semicolons in PRINT Statements; Practices 6, 7
Part 5 Scientific Notation 83
Objectives; Scientific Notation; Scientific Notation on the
TI-99/4A; Review and Feedback; Practice 8
Part 6 Relational Operators and IF-THEN/GOTO Statements 91
Objectives; Definition of Relational Operators; Key Words
(IF-THEN); Using IF-THEN Statements (Conditional
Branching); A Counting Program; Key Word (GOTO);
Using GOTO Statements (Unconditional Branching);
Practices 9, 10
Part 7 The INPUT Statement 103
Objectives; Key Word (INPUT); Using INPUT Statements;
String Variables; Practices 11, 12, 13
Part 8 Using the Calculator Mode 117
Objectives; Order of Operations (Review); Using the
Calculator or Immediate Mode; Command (NEW); Practice 14
Part 9 Using the Cassette Recorder 123
Objectives; Commands (SAVE, OLD); Using the Cassette
Recorder as an Input/Output Device; Check Tape Option;
Practices 15, 16, 17
Part 10 Using FOR-NEXT. . . STEP Statements 131
Objectives; Keywords (FOR-NEXT... STEP); Comparison
of GOTO, IF-THEN, and FOR-NEXT Program Loops; Loop
Flowcharts; Timer Loops; Practices 18, 19
Part 11 Reading Data 147
Objectives; Key Words (READ, DATA); Using READ-DATA
Statements; Key Word (RESTORE); Practice 20
Part 12 Video Display Graphics 159
Objectives; Video Display Layout; Video Display Worksheets;
Key Words (CALL HCHAR, CALL VCHAR, CALL CHAR);
Character Codes; Using Graphic Commands; Formatting
Output Using TAB Function; Practice 21
Part 13 Arrays 179
Objectives; Definition of an Array; Program Examples Using
One- and Two-Dimensional Arrays; Key Word (DIM);
Checkbook Array Program; Practices 22, 23
Part 14 INT(X), ABS(X), and RND Functions 193
Objectives; INT(X) Function; ABS(X) Function; RND
Function; RANDOMIZE Statement; Coin Toss Program;
Guess the Number Program; Practices 24, 25
Part 15 Subroutines 207
Objectives; Definition of a Subroutine; Key Words (GOSUB,
ON-GOTO, ON-GOSUB); Using Subroutines; Temperature
Conversion Program; A Quiz Program; Practices 26, 27
Extra Practices 224
I Speok BASIC
to My
TI-99/4A
Hardware (T^e f^chmes^^^^^^^^^^^^
What You Will Learn
1. That the computer is a valuable tool that can solve problems, print words,
draw pictures, store information, retrieve information, compare information,
play games, and do many other things to help you in everyday life.
2. That people control computers and that computers cannot think (despite
what you might have heard).
3. To identify and explain the basic parts of a computer and relate them to a
"box diagram" of a general purpose computer.
4. To identify and explain the function of the basic parts of a TI-99/4A
microcomputer.
5. To define and explain the terms hardware, software, microcomputer, micro-
processor, RAM, ROM, processor, input unit, output unit, and memory.
6. That computers are simple and easy to use; and above all that computers
are fun!
1
Welcome to the World of Computers
People Control Computers!
Computers Con't Think!
• Let's destroy some myths. First of all, despite what you might have heard,
people control computers, people design them, people build them, people
sell them, and, most of all, people tell them what to do (which is another
way of saying that people "program" them).
• A computer program is a set of instructions that specify what the computer
must do. Computer programmers write these instructions.
2
Box Diogrom of Typicol Doto Processing
Operotion
• INPUT
• PROCESSING
• OUTPUT
I i.2
Examples of Doto Processing Operation
• Data are collections or representations of facts or instructions.
• Although a computer isn't necessary to perform a data processing
operation, a computer system is capable of processing data at tremendous
speeds.
INPUT PROCESSING OUTPUT
(CALCULATE)
1. NUMBER HR WORKED
(40 hr)
2. RATE/HR
($3.00/HR)
40hr X 3.00/hr
= $120
PAY TO XXXX
$120
PAYCHECK
INPUT PROCESSING OUTPUT
(CALCULATE)
1 TOTAL NUMBER OP STUDENTS ^
1. TOTAL ALL GRADES
2. TOTAL ALL STUDENTS
IN CLASS
^
AVG
2. GRADES FOR EACH
3. TOTAL GRADES
TOTAL STUDENTS
>
GRADE
STUDENT
3
110
Terms You Should Know
• HAIU>WARE
— The computer and computer-related equipment
(the machines)
• SOFTWARE
— The instructions for the computer (the program)
114
Dox Diogrom Showing
of o Computer
r
• INPUT
UNIT
• STORAGE
UNIT
I
Ports
• PROCESSOR
UNIT
• OUTPUT
UNIT
4
11.5
Stores or Kemembers
Storage unit (memory)
— Stores both information and
instructions untii
needed (requested)
Computers are controlled by the program which is in the main storage unit.
1.6
Interprets, Controls, ond Colculotes
• PROCESSOR UNIT
- INTERPRETS (DECODES) INSTRUCTIONS
AND REGULATES (CONTROLS) THEIR EXECUTION
- PERFORMS ALL OF THE
CALCULATIONS
5
117
Dox Diogrom of o Computer System
• DATA
• INSTRUCTIONS
STORAGE
UNIT
PROCESSOR
UNIT
• INTERPRETS
&
CONTROLS
• PERFORMS
CALCULATIONS
STORES
OR
REMEMBERS
OUTPUT
UNIT
• RESULTS
• ANSWERS
18
Whot We Hove Leomed
• Input
• Storage
• Processor
• Output
Provides instructions and data
Stores or remembers (memory)
Interprets, controls, and calculates
Provides answers and results
6
19
"Human Computer''
Mon Con Think but Computer Con't!
EXECUTE (PERFORM WHATEVER OPERATION IS NECESSARY)
1 1,10
More Terms You Should Know
• Microprocessor = Very smaW processor.
• Microcomputer = Very small computer
• RAM = Random Access Memory
— CAN be changed by the user
— Information stored in RAM will be destroyed if power fails or is turned off
(volatile)
• ROM = Read Only Memory
— CANNOT be changed by the user
— Information stored in ROM is not destroyed if power fails or is turned off
(nonvolatile)
— Control program (BASIC interpreter) stored here
8
1111
Dox Diogrom of o Microcomputer
• STORAGE
UNIT
• INPUT
• MICROPROCESSOR
UNIT
UNIT
• OUTPUT
UNIT
9
PM2
Dosk Components of the
TI-99/4A Computer
r
KEYBOARDi
INPUT
MICRO-
PROCESSOR
PRINTER
OUTPUT
VIDEO
DISPLAY
OUTPUT
TAPE RECORDER
(I/O DEVICE)
10
1.13
TI-99/4A Computer System
1 114
What We Hove Leorned
DATA PROCESSING
OPERATION
STEPS:
BASIC
COMPUTER
PARTS:
MICROCOMPUTER
PARTS:
• INPUT
• PROCESSING
• OUTPUT
INPUT UNIT
• PROCESSOR UNIT
+
MEMORY UNIT
OUTPUT UNIT
• INPUT UNIT
• MICROPROCESSOR
+
MEMORY
• OUTPUT UNIT
PRACTICE 1
Dox Diagram of a Computer
1 . Draw the box diagram of a computer system.
a. Label each box with the correct name.
b. List the functions of each box.
12
Software (The ''Program'')
What You Will Learn
1. To define the terms hardware, software, BASIC, binary, and interpreter,
and to relate them to computers.
2. That computers speak a foreign language: machine language.
3. How humans talk to computers via a programming language called BASIC.
4. To identify the principal parts of a BASIC program.
5. To identify and explain the purpose of all the keys on the TI-99/4A
keyboard.
6. How to connect and power up a TI-99/4A microcomputer.
I REVIEW
Dox Diogrom of o Computer System
INPUT
UNIT
• DATA
• INSTRUCTIONS
STORAGE
UNIT
I
PROCESSOR
UNIT
• INTERPRETS
&
CONTROLS
• PERFORMS
CALCULATIONS
STORES
OR
REMEMBERS
OUTPUT
UNIT
• RESULTS
• ANSWERS
REVIEW
Terms You Should Know
• HARDWARE
— The computer and computer-related equipment
(the machines)
• SOFTWARE
— The instructions for the computer (the program)
14
^,1
Computers Speok o Foreign Longuogel
(No Speok English, French, Germon, Sponish,
or Any Other Noturol Longuoge)
• Computers speak in machine language
— Machine language is a form of binary coding
— Binary is a word denoting "two"
— Machine language uses two symbols: "0" and "1"
• A computer is capable of executing only machine language instructions.
15
Machine Language: Dit
Bit = binary digit
Bit = smallest memory cell in a computer
Bit = "1" or "0"
• Machine language instructions are stored in tlie main computer storage
of tine processor unit.
• Tliese instructions are coded in bits.
12.0
Machine Language: Dyte
1
Memory Cell with 1 Bit
8 Memory Cells
1
1
1
1
1
8 Bits = 1 Byte
• A bit was found to be insufficient to store all the letters of the alphabet,
special characters, and numbers needed to process data.
• A byte is a series of 8 bits.
• A byte is used to store a single letter, number, or character. For example, a
byte might contain the binary equivalent of the letter "A" or the number "7."
16
Machine Language: KDyte
Byte = 8 Bits
K = 1000
KBytes = 1000 Bytes
KBytes = 8000 Bits
• More exactly, a byte = 210 (1024) bits, but you need know only that K
stands for "one thousand."
• Microcomputers use RAM as their main computer storage. A 32K micro-
computer is one that has 32000 (or more exactly, 32768) bytes of RAM.
17
How Humons Talk to Computers
NATURAL
LANGUAGE
PROGRAMMING
LANGUAGE
• ENGLISH
— THINK
• BASIC
— WRITE
• INTERPRETER
- INTERPRET
MACHINE
LANGUAGE
CODE
• MACHINE
- EXECUTE
• Even though a computer can execute only machine language instructions,
it is not necessary to learn machine language to communicate with a
computer.
• People normally start to speak with their natural language, but we need a
programming language to talk to a computer.
• A program, located in ROM in a microcomputer and called an interpreter
program, interprets or translates a programming language into machine
language.
• There are many programming languages, some of which are COBOL
(Common Business Oriented Language), FORTRAN (Formula Translation),
RPG (Report Program Generator), PL/1, Pascal, and BASIC (Beginners
All-purpose Symbolic Instruction Code).
18
2.6
Terms You Should Know
• BASIC
(Beginner's All-purpose Symbolic Instruction Code)
— Popular programming language for writing instructions
to the computer
• Interpreter
-- Translates BASIC into machine code
— (You really don't have to know anything about an
interpreter since it is used automatically when you run a
BASIC program)
— Located in the ROM in the TI-99/4A
19
A Comparison between English ond BASIC
To Program You Must Learn the Language First!
English Language
• Words
— Used to make sentences
• Sentences
— Used to make paragraphs
• Paragraphs
— Lengths vary
• Commands
— Can be one word — e.g.,
STOP! HALT!
• Sentence Numbers
— Optional (seldom used)
BASIC Programming Language
• Keywords
— Used to make statements
• Statements
— Used to make programs
• Programs
— Lengths vary
• Commands
— Executed immediately — e.g.,
NEW, LIST, RUN
• Line Numbers
— Must be used for each statement
20
\2.Q
L#Giming o New Vocobulory
Here Are the Key Words and Commands You'll Learn:
Key Words
Commands
• PRINT
« NEW
• END
• LIST
• LET
• RUN
• INPUT
• CONTINUE
• GOTO
• IF-THEN
• REM
• STOP
• FOR-NEXT
• READ-DATA
12.9
Commands versus Statements
COMMANDS
— Executed as soon as you type them and press lENTER
STATEIVIENTS
— Put into programs and exe cuted on ly after you type the
command RUN and press [ENTER
21
12.10
A Program in DASIC
Line
Other Part
Number
Keyword
of the Statement
1st
statement
10
PRINT
"HELLO THERE"
2nd
Statement
20
PRINT
"YOUR NAME"
3rd
Statement
30
END
Command
RUN
"Look at"
Request®
ENTER
lENTERI
Enter
ENTER
Note:
® Pressing the ENTERI key tells the computer to "look at" (and store) what you have
just typed. You must press this key after each statement or command.
22
12,11
Line Numbers
• Serve as a guide to the computer in running tine program
• Tell the computer in what order it should carry out your instructions
• Normally are multiples of 5's, 10's, or some other multiples to leave space
for inserting new program lines between old ones
Note:
O Computer will start executing at lowest numbered line unless told to start
elsewhere.
O Although it is perfectly legal to number program lines more closely
(like 1, 2, 3, 4, etc.), don't do it!
12,12
Key Words
• Never used alone
• Need line number
• Always part of a BASIC statement that has some other part to it
• Executed only after command RUN is typed and [ENTER I key is pressed
23
[230
What We Hove Learned
Key words
— Used to make statements
Statements
— Must have line numbers and key words
— Used to make programs
Programs
— May vary in length
Commands
— Executed as soon as you type them and press I ENTER
24
Photo Courtesy of Texas Instruments Incorporated
12,15
Special Function Keys on thie
TI-99/4A Keyboard
KEY
FUNCTION
ENTER
ALPHA
LOCK
SHIFT
• Causes the computer to "look at" the line you just typed in and to act
accordingly. The key must be pressed each time you want to enter a
line from the keyboard.
— You may u se up to four screen lines for each program line before
you press I ENTER! .
— EH or 03 keys work exactly t he same as the [ENIERI key except in
Edit mode. (Refer to IFCTNI E and IFCTNI [X] below.)
• Pressing this key until it "clicks" into place locks all of the alphabetical
keys into the Upper-case mode. The number and pun ctuation keys are
not affected, however. To release the lALPHA/LOCKl key, just press
the key again and the keyboard returns to the Lower-case mode.
— You will use the computer with the lALPHA/LOCKl key down
(Upper-case mode) for all the lessons in this book.
• So me keys have two characters or symbols printed on the top. Use
the ISHIFTI key to type upper-case characters like the exclamation
mark (!), number symbol (#), doll ar sign ( $), ampersand (&), asterisk
(*), and percent symbol (%). The ISHIFTI key must be held down
while pressing a key to obtain the shifted character of that key.
— In the Lower-case mode, pressing the ISHIFTI key while pressing
any letter key will display the upper-case (capital) character of that
letter.
SPACE BAR
Operates just like the sp ace bar on a regular typewriter. When you
press the ISPACE BA"Rl . the computer leaves a blank space between
words, letters, or numbers.
— The ISPACE BA"Rl can be used to correct errors. This will be
explained in the section on Editing.
26
KEY
FUNCTION
CTRL
Stands for "CONTROL." This key is used primarily for telecommunica-
tions to permit entry of sp ecial co ntrol characters. To enter a control
character, hold down the ICTRLI key and press the appropriate letter
or number key. (For a list of Standard ASCII control characters, refer
to the Appendix of the User's Reference Guide.)
FCTN
Stands for "FUNCTION." Several keys h ave an additional function that
is obtained by holding down the I FCTN I key while the other keys are
pressed.
— Most of the functions — "AID," "CLEAR," "QUIT" etc. — are identi-
fied on the strip overlay packed with the computer. (If you have not
inserted this strip into the slot above the top row of keys on the
keyboard, do it now!)
Note that certain symbols (D,
front of several letter keys.
',[,], ?, ", etc.) are printed on the
FCTN
1
(DELete)
FCTN
2
(INSert)
Holding down the I FCTN! key while pressing the [U key will permit
you to delete characters from the program line. To delete characters,
position the cursor (using the f^or fel key) over the character you
wish to delete, then press the IFCTNI and {t} keys.
Puts the computer in Insert mode and permits you to insert characters
into the middle of a program line. To insert characters, position the
cursor (using the or key) over the character immediately to
the righ t of the place you wish to insert characters, then press the
IFCTNI and [2] keys (the computer is now in Insert mode). After you
have pressed these keys, each time you type a character, the cursor
and every character of the program line that is not to the left of the
cursor are moved to the right.
— Each character you type is inserted into the blank position left by
the shifting of the cursor and other characters.
— Note that characters shifted off the end of the program line are
deleted from the line.
— To get out of Insert mode, press the I ENTER I key.
FCTN
(ERASE)
Erases the entire program line, includ ing the l ine number you are
retyping, if you tiave not pressed the lENTERI key.
— If the computer is in Edit mode, however, the entire line displayed
for editing is erased except ttie line number.
27
KEY
FUNCTION
• When you press the IFCTNI [4] keys, you can perform several
functions, depending on when you press these l<eys.
— If a program is running, pressing IFCTNI [4] stops the execution of
the program. The message BREAKPOINT AT LINE NUMBER is
displayed . To continue execution, type CONTINUE and then press
lENTERl .
— If you are ty ping in a program line but do not wish to enter it,
pressing the IFCTNI S] keys causes the program line to scroll
(move) up on the scr een, but t hat line is not entered (because you
have not pressed the lENTERl key yet).
— If the computer is in Edit mode, the current line scrolls up on the
screen and the computer leave s Edit m ode. Any changes you made
on the line before pressing the IFCTNI {4} keys are ignored. That
is, the existing program line does not change.
FCTN
5
(BEGIN)
FCTN
6
(PROC'D)
FCTN
7
(AID)
FCTN
8
(REDO)
FCTN
9
(BACK)
• These keys (BEGIN, PROC'D, AID, REDO, and BACK) have special
functions with software applications and will not be covered in this
book. (Applications packages or software packages are programs that
have been written for the user. These packages include games,
mathematics courseware, personal record keeping, and the like.
or cursor right key moves the cursor to the right one character
position. The cursor does not erase or change the characters on the
screen as it passes over them.
— When the cursor reaches the end of a line on the screen, it wraps
around the screen and moves to the beginning of the next line
down. (Note! When the cursor reaches the end of its "logical line,"
which is four screen lines, pressing the[^ has no effect.)
FCTN
(CLEAR
or BREAK)
FCTN
D
([^)
or
(Forwardspace)
28
KEY
FUNCTION
FCTN S
(IS)
or
(Backspace)
or cursor left moves the cursor to the left one character position.
Using the does not delete or change the character it passes over.
— When the cursor reaches the end of a line, it wraps around and
moves up one row and to the extreme right-hand end of the row.
(Note! If the cursor reaches the beginning of the line, pressing the
key has no effect.)
FCTN
E
(ES)
FCTN
X
• The up-arrow {^) and down-arrow keys work exactly like the
I ENTER I key, except in Edit mode. (The Edit mode will be explained
on subsequent pages.)
m)
FCTN =
(QUIT)
You press these keys any time you want the computer to return to the
master screen, i.e., the screen you see when the computer is first
turned on.
— When you press these keys, all data or program information you
entered will be erased.
29
12,16
Symbols Displayed with I SHIFT I Key
Held Down
These symbols appear as the upper symbols on keys with two characters:
SYMBOLS
#
$
%
A
&
*
(
)
+
<
>
NAME
Exclamation
point
At sign
Number or
pound sign
Dollar sign
Percent
Caret
(exponentiation)
Ampersand
Asterisk
Open
parentliesis
Close
parenthesis
Plus sign
IVIinus sign
Less than
Greater than
Colon
HOLD DOWN
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
SHIFT
THEN PRESS
m
SHIFT
a
m
m
m
m
a
B
\T\ (comma)
□ (period)
Q] (semicolon)
30
1 2.M
Symbols Displayed with I FCTN I Key
Held Down
These symbols appear on the front of keys:
SYMBOLS
[
{
}
\
\
NAME HOLD DOWN THEN PRESS
Tilde
FCTN
Iwl
Open bracket
FCTN
[Rl
Close bracket
FCTN
B
Line
FCTN
Question mark
FCTN
m
Apostrophe
FCTN
m
Quote
FCTN
E
FCTN
Left brace
FCTN
(B
Right brace
FCTN
m
Reverse slant
FCTN
z
Reverse slant
FCTN
c
31
2.16
TI-99/4A Power-Up Rules
YOUR ACTION
1. Make certain the TI-99/4A micro-
computer is connected properly (refer
to the User's Reference Guide if you
have questions).
2. If the tape recorder is connected, it
should be in the STOP mode. (This
procedure assumes that you are not
using a disk.)
3. Turn on the video display and set the
RF modulator to "Modulator." (Make
certain that channel selection on the
television knob matches that on the
computer.)
4. Turn on the TI-99/4A. The power switch
is located on the lower-right front of the
console.
6. After a few seconds the message should
appear on the screen as shown.
DISPLAY
Press any key on the keyboard and you
will see:
7. Now press [T] on the keyboard to select
TI BASIC. The screen will appear as
shown and you are ready to use TI
BASIC.
TEXAS INSTRUMENTS
HOME COMPUTER
READY-PRESS ANY KEY TO BEGIN
^ ©1981 TEXAS INSTRUMENTS ^
f rv- TEXAS INSTRUMENTS
^ HOME COMPUTER
PRESS
1 FOR TI BASIC
TI BASIC READY
>■ ^-(cursor)
Note:
O Whenever the flashing cursor (■) appears on the screen, the computer is waiting for
you to enter something from the keyboard. The prompt character (>) marks the
beginning of each line.
32
PIUCTICE 2
Becoming Familiar with Your TI-99/4A
Become familiar with the TI-99/4A microcomputer by doing the following:
1 . Turn on the TI-99/4A using the Power-Up Rules (see page 32).
2. Where is the On-Off switch for the console located?
3. Locate the jSHIFTI key.
a. How many [SHIFT I keys are there on the keyboard? .
b. Hold down the ISHIFTI key and press every key that has a second symbol on it
(e.g., pressing [T] and [2]). What happened?.
(Note! If you see some symbols appear on the screen, don't worry about what they are
used for because you will learn about them later.)
c. What happens if you hold down the ISHIFTI key and press Q] , [3] , [6] , [8] , and g?
4. Locate the IFCTNI key
a. Hold down the IFCTNI key and press every key with a symbol on the front of it except the
and \X\ keys. What happened?
What keys do you press to get a quote ("), question mark (?), apostrophe ('), and open
bracket ([)?
Type CAL L CLEA R to clear the screen. Then move the cursor right ([^) by holding
down the IFCTNI key while pressing \D\. Starting at the beginning of a line (>), move
the cursor until it stops. How many lines did it move before it stopped?
d. Now move the cursor left ([^) by holding down the IFCTNI key while pressing [s].
How far did the cursor move before it stopped?.
e. Hold down the IFCTN I key while pressing the [=] key. What happened?.
5. Note that all the keys have a repeat feature that keeps the cursor moving or causes the
character to repeat until you release the key. (You try it!)
6. With the computer, you cannot type the letter "L" as the number "1 ." Also, you should
never substitute the letter "O" for the number zero. A slash (0) is used to help you
recognize a zero on the keyboard only. The computer screen displays the letter "O"
with squared corners and displays a zero with rounded "O" corners to help you
distinguish them. But it is still difficult to distinguish them on the screen unless you
know the difference. Experiment by typing a zero and then the letter "O" until you
recognize the differen ce on the screen.
7. Beware of the I QUIT I key! Holding down the IFCTNI key while pressing the [=] key
causes the computer to erase all data or program material you have entered.
33
Your First Computer
Progrom
What You Will Learn
1. To enter and RUN your first BASIC program.
2. To explain the purpose and use of the following BASIC commands:
CALL CLEAR, LIST, NEW, RUN.
3. To explain the purpose and use of the following key words:
PRINT, REM, END.
4. To explain the purpose and use of the following special function keys:
CLEAR . ENTER . SHIFTl. |<^|. ALPHA/LOCK , CTRL , FCTN
5. To explain the purpose and use of the following miscellaneous points:
> (prompt), ■ (cursor), "" (quotes), line numbers, power-up rules.
35
REVIEW
Special Function Keys on the
TI-99/4A Keyboard
KEY
FUNCTION
ENTER
Causes the computer to "look at" the line you just typed in and to act
accordingly. The key must be pressed each time you want to enter a
line from the keyboard.
— You may u se up to four screen lines for each program line before
you press lENTERI .
23 or keys work exactly the same as the I ENTER] key except in
Edit mode. (Refer to IFCTNI E and IFCTNI \X\ below.)
ALPHA
LOCK
Pressing this key until it "clicks" into place locks all of the alphabetical
keys into the Upper-case mode. The number and pun ctuation keys are
not affected, however. To release the lALPHA/LOCKI key, just press
the key again and the keyboard returns to the Lower-case mode.
— You will use the computer with the lALPHA/LOCKI key down
(Upper-case mode) for all the lessons in this book.
SHIFT
So me keys have two characters or symbols printed on the top. Use
the ISHIFTI key to type upper-case characters like the exclamation
mark (!), number symbol (#), doll ar sign ( $), ampersand (&), asterisk
(*), and percent symbol (%). The ISHIFTI key must be held down
while pressing a key to obtain the shifted character of that key.
— In the Lower-case mode, pressing the ISHIFTI key while pressing
any letter key will display the upper-case (capital) character of that
letter.
SPACE BAR
• Operates just like the sp ace bar on a regular typewriter. When you
press the ISPACE BARl . the computer leaves a blank space between
words, letters, or numbers.
The ISPACE BARl can be used to correct errors. This will be
explained in the section on Editing.
36
KEY
FUNCTION
CTRL
Stands for "CONTROL." This key is used primarily for telecommunica-
tions to permit entry of sp ecial co ntrol characters. To enter a control
character, hold down the ICTRLI key and press the appcopriate letter
or number key. (For a list of Standard ASCII control characters, refer
to the Appendix of the User's Reference Guide.)
FCTN
Stands for "FUNCTION." Several keys h ave an additional function that
is obtained by holding down the I FCTN I key while the other keys are
pressed.
— Most of the functions — "AID," "CLEAR," "QUIT" etc. — are identi-
fied on the strip overlay packed with the computer. (If you have not
inserted this strip into the slot above the top row of keys on the
keyboard, do it now!)
— Note that certain symbols (1}, - [, ], ?, ", etc.) are printed on the
front of several letter keys.
FCTN
1
(DELete)
FCTN
2
(INSert)
• Holding down the IFCTNI key while pressing the \T\ key will permit
you to delete characters from the program line. To delete characters,
position the cursor (using the l^or F^ key) over the character you
wish to delete, then press the IFCTNI and [T] keys.
• Puts the computer in Insert mode and permits you to insert characters
into the middle of a program line. To insert characters, position the
cursor (using the or key) over the character immediately to
the righ t of the place you wish to insert characters, then press the
IFCTNI and [2] keys (the computer is now in Insert mode). After you
have pressed these keys, each time you type a character, the cursor
and every character of the program line that is not to the left of the
cursor are moved to the right.
— Each character you type is inserted into the blank position left by
the shifting of the cursor and other characters.
— Note that characters shifted off the end of the program line are
deleted from the line.
— To get out of Insert mode, press the I ENTER I key.
FCTN
(ERASE)
Erases the entire program line, includ ing the li ne number you are
retyping, if you fiave not pressed the ENTER I key.
— If the computer is in Edit mode, however, the entire line displayed
for editing is erased except the line number.
37
KEY
FUNCTION
FCTN 4
(CLEAR
or BREAK)
When you press the I FCTN I [4] keys, you can perform several
functions, depending on when you press these keys.
— If a program is running, pressing I FCTN I [4] stops the execution of
the program. The message BREAKPOINT AT LINE NUMBER is
displayed. To continue execution, type CONTINUE and then press
lENTERI .
— If you are ty ping in a program line but do not wish to enter it,
pressing the I FCTN I 3] keys causes the program line to scroll
(move) up on the scr een, but t hat line is not entered (because you
have not pressed the lENTERI key yet).
— If the computer is in Edit mode, the current line scrolls up on the
screen and the computer leave s Edit m ode. Any changes you made
on the line before pressing the I FCTN I [4] keys are ignored. That
is, the existing program line does not change.
FCTN
5
(BEGIN)
FCTN
6
(PROC'D)
FCTN
7
(AID)
FCTN
8
(REDO)
FCTN
9
• These keys (BEGIN, PROCD, AID, REDO, and BACK) have special
functions with software applications and will not be covered in this
book. (Applications packages or software packages are programs that
have been written for the user. These packages include games,
mathematics courseware, personal record keeping, and the like.
(BACK)
FCTN D
([^)
or
(Forwardspace)
or cursor right key moves the cursor to the right one character
position. The cursor does not erase or change the characters on the
screen as it passes over them.
— When the cursor reaches the end of a line on the screen, it wraps
around the screen and moves to the beginning of the next line
down. (Note! When the cursor reaches the end of its "logical line,"
which is four screen lines, pressing the[^ has no effect.)
38
KEY
FUNCTION
FCTN S
(IS)
or
(Backspace)
or cursor left moves the cursor to the left one character position.
Using the |^ does not delete or change the character it passes over.
— When the cursor reaches the end of a line, it wraps around and
moves up one row and to the extreme right-hand end of the row.
(Note! If the cursor reaches the beginning of the line, pressing the
key has no effect.)
FCTN
E
(El)
FCTN
X
• The up-a rrow (El) and down-arrow (23) keys work exactly like the
I ENTER I key, except in Edit mode. (The Edit mode will be explained
on subsequent pages.)
FCTN =
(QUIT)
You press these keys any time you want the computer to return to the
master screen, i.e., the screen you see when the computer is first
turned on.
— When you press these keys, all data or program information you
entered will be erased.
39
REVIEW
TI-99/4A Power-Up Kules
YOUR ACTION
1. Make certain the TI-99/4A micro-
computer is connected properly (refer
to the User's Reference Guide if you
have questions).
2. If the tape recorder is connected, it
should be in the STOP mode. (This
procedure assumes that you are not
using a disk.)
3. Turn on the video display and set the
RF modulator to "Modulator." (Make
certain that channel selection on the
television knob matches that on the
computer.)
4. Turn on the TI-99/4A. The power switch
is located on the lower-right front of the
console.
5. After a few seconds the message should
appear on the screen as shown.
Press any key on the keyboard and you
will see:
7. Now press [T] on the keyboard to select
TI BASIC. The screen will appear as
shown and you are ready to use TI
BASIC.
DISPLAY
TEXAS INSTRUMENTS
HOME COMPUTER
READY-PRESS ANY KEY TO BEGIN
. ©1981 TEXAS INSTRUMENTS ,
TEXAS INSTRUMENTS
HONE CONPUTER
PRESS
1 FOR TI BASIC
J
TI BASIC READY
>■ Hcursor)
Note:
O Whenever the flashing cursor (■) appears on the screen, the computer is waiting for
you to enter something from the l<eyboard. The prompt character (>) marks the
beginning of each line.
40
Getting It Together
• step 1 — Write Your Program
• Step 2 — Get the Computer Ready
• Step 3 — Enter Your BASIC Program
• Step 4 — RUN Your Program
• Step 5 — Sign Off
Note:
O Step 5 means turning the computer off when you have finished
programming.
41
Typical Display Readout
10 PRINT "HELLO THERE"
20 PRINT "YOUR NAME"
30 END
RUN
V J
42
Writing Your First Computer Progrom
YOUR ACTION
DISPLAY
1. Before you start typing your program,
always ty pe NEW and press the
I enter] key.
Type the line exactly as shown:
3. Use the IFCTNI key to type th e quota-
tion marks (") and the ISHIFTI key for
the exclamation point (I).
4. Do not press the lENTERI key yet!
5. Go back and examine your typed line
very carefully. Did you make a mistake?
If yo u did, ju st press the backspace key
\M ( IFCTNI Is] j to move the cursor
back to that point and then type the
correct character(s).
Is everyt hing OK? If it is, you can press
ENT ERI. (This tells the computer to
6.
"look at" what you just typed in).
>TI BASIC READY
>■
>10 PRINT "HELLO THERE NAME!"
>10 PRINT "HELLO THERE NAME!"
>■
7. The prompt > and cursor ■ should
appear. The computer is saying, "It's
your turn . . . Tm waiting for you."
Note:
O NEW is a command that erases any program that may have been in the computer's
memory, and typing NEW is an important first step in programming.
(A) Insert student's name.
(B) A slash is used in this book to distinguish a zero (0) from the letter "O." Your screen,
however, will not display the slash.
© The TI-99/4A has 28 columns across the screen. If the line you typed has more
than 28 characters (including spaces, numbers, and symbols), the characters will "spill
over" or "wrap around" to the next line automatically.
43
Executing Your Program
YOUR ACTION
DISPLAY
1 . Tell the computer to execute or run your
program. The command for this is
simple: RUN.
2. So type RUN and press I ENTER I
3. If you made no mistakes, the display
will read:
4. If it did not work, try again (i.e., check
your program for errors).
5. If it did work, let out a yell, "HEY, I CAN
DO IT TOO!"
Go to next page (if you completed this
one OK).
>RUN
HELLO THERE NAME!
•* DONE "
>■
44
10,5
Common Errors
Missing quotes (")
Too many quotes
Forgot the key word PRINT
Forgot the line number
Forgot to press [ENTER
• Used the character "O" for the number "zero" (0).
Note:
O A slash is used to help you recognize a zero. Look at your keyboard
closely. The computer screen, however, displays the letter "O" with
squared corners and a zero with rounded corners. Make certain you can
distinguish between them!
45
10.6
Writing Your First Computer Progrom
— Almost? (Correcting Errors)
PROBLEMS: (You forgot to follow instructions.)
1. Missing Quotes (")
— You forgot to enclose everything after the word PRINT in quotation
marks. Don't forget to use quotation marks if you want something
printed!
2. Too IVIany Quotation l\/larl(s
— You typed too many. That won't work either!
3. Forgot the Key Word PRINT
— You forgot to type PRINT. How will the computer know to PRINT
something if you don't tell it to?
4. Forgot to Type the Line Number
— Line numbers tell the computer where to start. The computer always
starts executing from the lowest numbered line unless you tell it to
start elsewhere.
SOLUTION:
If you have already pressed lENTERI , you must retype the entire line to
correct your error.
Type in the same line number you wish to change.
Retype the line exactly as shown on the previous page. (But this time,
be more careful!)
Then, check the line over for errors.
If everything is OK, don't forget to press I ENTER I ! Pressing I ENTER
tells the computer to "look at" what you just typed and act accordingly.
Read this page if you had any errors! Then correct your errors before going
to the next page.
46
10 J
Expanding Your Program
YOUR ACTION
DISPLAY
2.
3.
6.
7.
You now have a program in the
computer (unless you turned it off. If
you did, retype the line as shown):
Type in Line 20 exactly as shown:
Check your new Line (20) very carefully,
especially the quotation marks.
4. Everything OK? Press I ENTER
(Remember, always press I ENTER I if
you want the computer to look at what
you typed.)
Let's r un your p rogram. Type RUN and
press I ENTER I .
If you did it right, the screen will read:
If it did not work, check your program
for errors.
Go to next page.
>10 PRINT "HELLO THERE NAME!"
>20 PRINT "I'M GOING TO MAKE
YOU A SUPERSTAR!"
>RUN
HELLO THERE NAME!
I'M GOING TO MAKE YOU A SURE
RSTAR!
DONE '
47
Using the PRINT Statement for Spacing
YOUR ACTION DISPLAY
1 . Look at your video display. Would you
like more space between the two lines?
OK, this is how you do it.
2. Type i n a new l ine as shown and then
press flNTERl .
3. Now type RUN and press I ENTER .
4. Wow! A PRINT "nothing" puts a space
between what you told the computer to
print in Lines 10 and 20.
5. Observe that the PRINT statement
(Line 15) was placed between Lines 10
and 20. Since you were smart enough
to number your lines by 10's, it was
much easier to modify your program.
(That's because you left room to insert
new lines between the old ones.)
Although it is perfectly legal to number
program lines more closely (like 1, 2,
3, 4), don't do it.
Go to next page.
48
HELLO THERE NAME!
I'M GOING TO MAKE YOU A SURE
RSTAR!
>1 5 PRINT
>■
>RUN
HELLO THERE NAME!
I'M GOING TO MAKE YOU A SURE
RSTAR!
** DONE **
>■
Inserting Remarks into o Program
(Dut Not Printing Them Out)
YOUR ACTION
DISPLAY
1. Type Line 5 and press I ENTER
2. Type RUN and press I ENTER I . (It is the
same output as before!)
Go to next page.
>5 REM THIS IS MY FIRST COMPU
TER PROGRAM
>RUN
HELLO THERE NAME!
I'M GOING TO MAKE YOU A SURE
RSTAR!
DONE •*
Note:
O REM stands for REMark. It is an important statement in BASIC.
O It is often convenient to insert REMarks into a program. The main reason for inserting
REMarks is so that you or someone else can refer to them later and know what the
program is for and how it is used.
O When yo u tell the computer to execute the program by typing RUN and pressing
I ENTER I , it will skip over any number line that begins with the statement REM. The
REM statement will have no effect on the output of the program!
49
13.10
Listing Your Program (Loolting ot
Your Program to See What It Contains)
YOUR ACTION
DISPLAY
1. Type CALL CLEAR and press I ENTER .
2. Type LIST and press I ENTER I : (You can
LIST your program anytime the prompt
> appears on the screen.
3. You might want to LIST only one line
Type LIST 20 and press I ENTER
(Make sure there is a space between
the word LIST and the line number,
otherwise you will get an INCORRECT
STATEMENT error.)
You might also want to LIST several
program lines, starting at one line and
ending at another. For example, type
LIST 10 - 20 and press I ENTER I .
Go to next page.
>LIST
5 REM THIS IS MY FIRST COMP
UTER PROGRAM
10 PRINT "HELLO THERE NAME!"
15 PRINT
20 PRINT "I'M GOING TO MAKE
YOU A SUPERSTAR!"
>■
>LIST 20
20 PRINT "I'M GOING TO MAKE
YOU A SUPERSTAR!"
>■
>LIST 10-20
10 PRINT "HELLO THERE NAME!"
15 PRINT
20 PRINT "I'M GOING TO MAKE
YOU A SUPERSTAR!"
>■
Note:
O CALL CLEAR is the command that will clear the screen. It's a good idea to do this
from time to time to make it easier to read.
50
Ending Your Program
YOUR ACTION
DISPLAY
1 . The end of a program is the last state-
ment you want the computer to execute.
Most computers require you to place
an END statement after this point, so
that the computer will know it is finished.
However, the TI-99/4A does not
require an END statement.
2. Lefs add an END statement to your
program. Type and I ENTER
3. Now type RUN and press I ENTER
4. No change from before! The program
ended, but it did not print "END."
5. Lefs make it print "THE END."
(How do we do that?)
6. Oh, I remember! We need a PRINT
statemen t. So let's try it. Type and
ENTER
7. Now RUN your program.
8. It worked again! (If not, check the
program.)
9. Note that there is no space between
"THE END" and the line above it. Why?
Because you did not tell the computer
to put a space between them!
>9g END
>RUN
HELLO THERE NAME!
I'M GOING TO MAKE YOU A SURE
RSTAR!"
□ONE
>l
>98 PRINT "THE END"
>RUN
HELLO THERE NAME!
I'M GOING TO MAKE YOU A SURE
RSTAR!
THE END
** DONE **
51
1 3.12 I
Using the Left-Arrow ([^) Key to Sove
Retype Time (Defoie You Piess the I ENTER! Key)
YOUR ACTION
You typed Li ne 10 as shown but have
not pressed [ENTER I (blinking cursor
at the end of that line indic ates you
have not pressed I ENTER I ).
You wish to change the "D" to a "B" or
to PRINT AUBREY. So you use the
key to move the cursor to
the left one spac e at a tim e. (Don't
forget to use the I FCTN I key.)
3. Now type "B" but don't press I ENTER
yet. (Note that the cursor has moved to
the next letter "R.")
4. If you have finished typing t he line a nd
everything is correct, pres s JENIlB
(Note that after you press
ENTER I
the blinking cursor moved to the begin-
ning of the next line.)
Remember you can always retype the
entire line but the key saves you
time.
DISPLAY
>10 PRINT "AUDREY"
t
(blinking cursor)
>10 PRINT "AL(|REY"
t
(blinking cursor)
>10 PRINT "AU^EY"
t
(cursor)
r
>10 PRINT "AUBREY"
^cursor)
Note:
O Type NEW before you start.
52
3.13
Some Tips on Editing
If you made a mistake in typing in a program line or if you wish to change an existing
program line, you can change a line by entering the Edit mode.
• Editing One Line Oniy
To enter Edit mode, yo u type th e EDIT command followed by a line number (e.g., EDIT
10 and then press the I ENTER! key).
— When you enter Edit mode, the program line you requested is displayed on the
screen. The prompt character (>) is not displayed to the left of the line when you are
in the Edit mode.
— When the requested line is displayed, the flashing cursor is positioned in the second
character position to the right of the line number (see example on next page).
— Changes can be made to any character on the line except the line number.
Editing Severai Lines
When you press the I ENTER I key, all changes you have made to the program line are
entered into the computer's memory and the computer leaves the Edit mode.
— If you want the computer to stay in Edit mo de beca use you want to make changes to
other program lines, then you should press IFCTNI and [E] (HJ) or lFCTNl and I
my
— Pressing the I FCTN I and [I] (QS) keys causes all changes you have made to the
program line to be entered into the computer's memory. The next lower-numbered
line in the program is then displayed for editing. If no lower program line exists, then
the computer leaves Edit mode. (Note that the cursor does not have to be at the end
of the line for the entire line to be entered by the key.)
Pressing the I FCTN l and [x] (O) keys causes all changes you made to the program line
to be entered into the computer's memory. The next higher-numbered program line is
then displayed by editing. .If no higher program line exists, then the computer leaves
the Edit mode. The cursor does not have to be at the end of the line for the entire line
to be entered by the [5] key.)
53
10,14
Using the Edit Mode to Correct Errors
(After You Hove Pressed the lENTEM Key)
YOUR ACTION
DISPLAY
1 . Type NEW and press I ENTER
2. Type i n Line 10 exactly as shown and
press I ENTER I .
3. Since you liave entered this line in the
computer, you must enter the Edit
mode by typing:
(Leave a space between the word "EDIT"
and "10".)
4. Now press I ENTER I . (Note the position
of the cursor.)
5. Move the cursor over the "I" in "IRROR"
by using the 1^ l<ey. ( Don't forget to
hold down the I FCTNI key.)
6. Change the " I" to "E" b y typing "E." (Do
not press the I ENTERI key yet!)
7. If this were the only change you wanted
to make, you would merely press the
ENTERI key to get out of Edit mode.
But let's change the word "IS" to "WAS."
a. Using the key, move the cursor
over the "I" in the word "IS."
b. Now type "A." (Note the position of
the cursor.)
>TI BASIC READY
>10 PRINT "THIS IS AN IRRQR"
r
>EDIT10
>EDIT10
10 [SRINT "THIS IS AN IRROR"
t
(cursor]
>EDIT 10
10 PRINT "THIS IS AN UlRROR"
\
(cursor)
>EDIT 10
10 PRINT "THIS IS AN ERROR"
\
(cursor]
>EDIT 10
10 PRINT "THIS QjS AN ERROR"
t
(cursor]
>EDIT10
10 PRINT "THIS AH AN ERROR"
t
(cursor]
54
3.14 (Cont.)
YOUR ACTION
DISPLAY
c. To insert a "W," position the cursor
over the "A" using the [^key. (Don't
forget to hold down the I FCTNl key!)
d. Press the IINSERTI key. (i.e., hold
down I FCTNl and press [2].
e. Now type "W" and you will see that a
"W" was inserted. (Notice that the
cursor moved to the right.)
f. If you have finished maki ng all of
your changes, press the I ENTER I key.
>EDIT10
10 PRINT "THIS laS AN ERROR"
t
(cursor)
>EDIT 10
10 PRINT "THIS [AlS AN ERROR"
t
(cursor still here]
>EDIT 10
10 PRINT "THIS W[A]S AN ERROR"
t
(cursor)
>EDIT10
10 PRINT "THIS WAS AN ERROR"
>l
55
10,15
Some Helpful Keys ond Commands
to Remember
ACTION
• Clear screen and
home cursor
• Enter data
• Execute a program
• Stop program
execution
• CONTINUE program
• LIST program
KEY(S) TO PRESS
EllAlEE (space bar) [CHHIKaIIB]
ENTER I . IFCTNI RFI. [FCTN
R
U
N
and
ENTER
FCTNl [4]( rCLEARl )
CllQlEldEDElOl] and I ENTER
iLimfSimand lENTER
FCTN
FCTN
FCTN] El ( [QUiT] )
FCTNl [3l ( [ERASE] )
• Backspace
(cursor left)
• Forward space
(cursor right)
• Return to
master screen
• Erase an entire
progra m line
(before I ENTER I key
is pressed
Note:
® When you press |QUIT| , all data or program material you have entered will
be erased.
COMMAND
CALL CLEAR
RUN
BREAK
STOP
END
CONTINUE
LIST
®
56
I0>16
Learned in This
COMMANDS'
• CALL CLEAR
• LIST
— LIST MM
• NEW
• RUN
* Executed as
soon as you
type t hem and
press I ENTER
KEY WORDS**
PRINT "MESSAGE"
PRINT (SPACE)
REM
END
*Used to make
statements.
Statements are
executed after
you ty pe RUN and
press lENTER
MISCELLANEOUS
> Prompt
■ Cursor
" " Quotation
Marks
Line Numbering
Keyboard
Layout
TI-99/4A
Power-Up Rules
QUIT I
DQNE
SPECIAL
FUNCTION
KEYS
FCTN
ENTER
ALPHA
LOCK
Note:
O IVIM = Any line number (e.g., 10, 20, 30, etc.)
O Always leave a space between a key word and a line number (MM); otherwise an error
will occur.
O You will use the computer with the I ALPHA/LOCK I key down (Upper-case mode) for
all lessons In this book.
O If you don't understand everything on this page, stop! Go back over this section until
you understand it thoroughly!
57
ASSIGNMENT 3-1
1. Write a program to print on separate lines:
a. Your name
b. Your entire address
c. Your telephone number
2. Expand your program to include the following:
a. REM statements to describe your program
b. Spacing between each of the lines displayed (printed)
c. An END statement
3. Type your program and enter it.
4. RUN your program.
5. LIST your program.
Note:
O Write your program on paper and get it checked by your teacher first.
58
^1 PRACTICE
Writing and Running Your Rrst Program
1 . Write a program to PRINT the following:
a. Your name (first and last)
b. Your school's name
c. Your teacher's name
2. Enter and RUN it.
PRACTICE 4
Inserting Remarks ond Spacing into
Your Program
1 . If you have erased the program from Practice 3, rewrite the program and do the following:
(If you still have the program from Practice 3 in the computer, you do not have to rewrite
the program.)
a. Add a new program line with a REM statement to your program (any remarks you want
to make).
b. Have the computer insert one space between your name and your school's name in the
output on the display (that is, you add the necessary program line).
c. Have the computer insert two spaces between your school's name and your teacher's
name in the output on the display.
^1 PRACTICE 5
Listing and Ending Your Program
1 . Rewrite the program from Practice 4 and do the following (Again, if you have the program in
the computer, you don't have to rewrite it. But in case you don't know what is in the computer,
just type NEW and rewrite the program.):
a. Add an END statement to tell the computer it is the end of your program.
b. Add a statement to have your computer PRINT 'THE END."
c. RUN your program.
2. LIST your program.
a. How large is your program now? (How many lines?)
b. Copy the program in your notebook.
59
More Programming Tools
What You Will Learn
1. To enter and RUN more BASIC programs: mathematical programs, area of
rectangle program.
2. To explain the order of mathematical operations using the M.D.A.S. rule.
3. To explain the purpose and use of the key word: LET.
4. To explain the purpose and use of the mathematic operators: multiply (*),
divide(/), add (+), subtract (— ). exponentiate or raise a number to a
power(A).
5. To explain the function and use of commas, semicolons, and PRINT zones.
6. To identify variables that can be used with Tl BASIC.
61
REVIEW
COMMANDS'
• CALL CLEAR
• LIST
— LIST MM
• NEW
• RUN
* Executed as
soon as you
type them and
press [ENTER
KEY WORDS**
PRINT "MESSAGE"
PRINT (SPACE)
REM
END
*Used to make
statements.
Statements are
executed after
you type RUN and
press [ENTER
MISCELLANEOUS
> Prompt
■ Cursor
" " Quotation
Marks
Line Numbering
Keyboard
Layout
TI-99/4A
Power-Up Rules
QUIT I
DONE
SPECIAL
FUNCTION
KEYS
FCTN
ENTER
ALPHA
LOCK
Note:
O MM = Any line number (e.g., 10, 20, 30, etc.)
O Always leave a space between a key word and a line number (MM); otherwise an error
will occur.
O You will use the computer with the lALPHA/LOCKl key down (Upper-case mode) for
all lessons in this book.
O 1^ you don't understand everything on this page, stop! Go back over this section until
you understand it thoroughly!
62
4.1
Moth Operators
= (Equals)
+ (Add)
— (Subtract)
* (Multiply)
/ (Divide)
A (Exponentiation)
Note:
O Exponentiation (A) means raising a number to a power like 22, 23, or 2\
Order of Arithmetic Operotions
• Multiply — Divide -* Add -* Subtract (left to right)
— "My Dear Aunt Sally"
• If parentheses are used:
— the innermost set of parentheses is simplified first, followed by each
successive set outward.
— the M.D.A.S. order is followed inside all sets of parentheses.
4.2
Order of Operations Example
(without Parentheses)
If there are no parentheses, the computer performs operations by going
from left to right doing exponentiation operations (A) first. Then (*) and (/)
are done in order from left to right and finally (+) and (— ) are done in order
from left to right. (Remember M.D.A.S.!)
Example:
4+5*4A3
4 + 5 *[64|
4+ |320]
4 + 320 - [2
4/2
4/2
4/2
324
- 2 = 322
64
14,4
Order of Operations Example
(with Parentheses)
If there are parentheses, the computer starts at the inner pair of parentheses
and converts everything to a single number. Then the computer repeats the
process with the next pair of parentheses working "inside" out.
Example:
( (6 + 4) * 2) /4 =
{ [10] *2)/4 =
20 /4 = 5
Note:
O The same answer can be worked out first on paper and then on the
computer. If you type in
PRINT ( (6+4) * 2) /4
and press lENTERl . the computer will print out 5.
65
EXERCISE 4-1
• You try some now (without parentheses).
1. 2A3 + 4*5-4/2*5 =
2. 14 - 2*2 + 6- 2*3*2 =
3. 14/2 * 3 - 2 A 3 + 4 =
• Now try some with parentheses.
1. 6 +(9* 2) =
2. (6 + (9 * 2) ) * 5 =
3. 3 * ( (4 + (6 * 2) ) * (9/3 - 1) ) =
Note:
O You should work these out on paper. If you use the computer to check
the answers, be sure to use the word PRINT and leave off the equals sign
(=). For example, type
PRINT2A3 + 4*5-4/2*5
and press I ENTER
66
SUMMARY
Tips on Using Parentheses
• When in doubt, use parentheses. They can't do any harm!
— Use parentheses around operations you want performed first.
• Make sure that every left parenthesis has a matching right parenthesis.
— Count them to be sure!
• Order of operations:
— Innermost pair of parentheses first (M.D.A.S. rule inside parentheses).
— Then work "inside" out.
— In case of a "tie," computer starts to the left and works right doing
exponentiation (A) and the M.D.A.S. rule.
Numeric Variable Names Used with Tl DASIC
• May be one or more characters in length
— up to 15 characters may be used
— must not be a reserved word (see below)
• Must begin with a letter (A-Z), an at sign (@), a left bracket ([), a right
bracket (]), a back slash (\), or a line ( )
— may be followed by another letter, the at sign (@), or the line ( )
or
— may be followed by a digit (0-9)
• Some examples of numeric variable names include:
— A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z.
— A1, A2, B1, 82, C3, C5, D9, N9, P4, Q1, R6, Y7
— AA, AZ, GP, MU, ZZ, BB, XY, LL, FG, LE, RE
— ALPHA, BASE, TOTAL, SUM, TABLE, NAME, DATE
(You get the picture! Using the above combinations, you can use
approximately 900 variable names.)
• There are some words with special meaning in the BASIC language and
they cannot be used as numeric variable names.
— The complete list of reserved words, which cannot be used in variable
names, appears in the Tl User's Reference Guide.
68
Program for o Mothemotkol Operotion
Line No.
10
20
30
40
99
RUN
Key Word
LET
LET
LET
PRINT
END
Other Part of
Statement
X = 5
Y = 12
Z = X*Y
Z
ENTER
ENTER
ENTER
ENTER
Note:
O LET is an optional key word for Tl BASIC. Some computers require you
to use LET, liowever. Beware of this if you use another computer.
O I ENTER I is not part of the program. It is just a reminder to press it after
each line.
69
Analysis of the Progrcim
for Q Mothemoticol Operotion
Line No. Statement Meaning to Computer
10 LET X = 5 Assign a value of 5 to variable X
20 LET Y = 12 Assign a value to 12 to variable Y
30 LET Z = X*Y Take the values of X and Y, multiply
them together, and assign the
resulting value to the variable Z
40 PRINT Z PRINTthevalueof Z (which is60 in
the example)
99 END END Program
RUN Execute Program
70
EXERCISE 4-2
igning Numeric Values to Variables
• Fill in the values of the variables on each line in the program.
10 LET A = 12
20LETB = 8-
30 LETC = A + B —
40LETD = A-B —
50 LET E=A*B
60 PRINT A;B;C;D;E
70 LET A = A* 10 —
80LETB = A+B —
90LETW = A+B —
100 PRINT W
110 END
s
•12
•►8
a
71
i4,e n
A MothemoticQl Program: Areo of Kectongle
YOUR ACTION
DISPLAY
1. Type NEW.
2. Type and enter.
3. Type RUN and press I ENTER
Tl BASIC READY
>1 REM AREA OF A RECTANGLE
>20 REM AREA = LENGTH X WIDTH
>30 LETL= 10
>40 LET W = 5
>50 LET A ^ L*W
>60 PRINT A
>RUN
50
DONE
Note:
O We said in Line 60 PRINT A. There were no quotes around the letter A because we
wanted the computer to PRINT the value of A. If we wanted the computer to PRINT
the exact word or letter, we would put quotes around the word or variable.
72
Area of Rectangle Program Modified
YOUR ACTION
DISPLAY
1. Add Line 70.
2. Type RUN.
3. Add Line 80.
4. Type RUN.
5. Add Lie 90.
6. Type RUN.
7. LIST the program.
>70 PRINT'THE AREA =":A
>RUN
50
THE AREA = 50
>80 PRINT'THE AREA IS".A
>RUN
50
THE AREA = 50
THE AREA tS 50
DONE '
AREA OF A RECTANGLE
AREA = LENGTH *WIDT
>LIST
10 REM
20 REM
H
30 LETL=10
40 LET W=5
50 LET A=L*W
60 PRINT A
70 PRINT "THE AREA =":A
80 PRINT "THE AREA IS".A
90 PRINT "THE AREA IS";A;"SQ
. INCHES"
>■
Note:
(A) The semicolon in Line 70 caused the value of A to be PRINTed next to a label,
namely, THE AREA =.
>90 PRINT'THE AREA IS";A:"SQ.
INCHES"
>RUN
50
THE AREA = 50
THE AREA IS 50
THE AREA IS 50 SQ.INCHES
73
(B) The comma in Line 80 caused the value of A to be PRINTed separated from a label.
© The semicolons in Line 90 caused the value of A to be PRINTed between two labels.
A space is automatically inserted before and after a numeric variable when PRINTed.
This may not be true for other microcomputers.
(6) There are four different outputs in this RUN since the program contained four different
PRINT statements (Lines 60, 70, 80, and 90).
ASSIGNMENT 4-1
1 . Write a program to find the area of a triangle.
a. GIVEN: A = 1/2BH where B = 5, H = 10
b. Include REM statements
c. Have the program PRINT "THE AREA="; (your answer); "SQ. FT."
2. Write a program to find the volume of a rectangular solid.
a. GIVEN: V = LWH where L = 5, W = 10, H = 2
b. Include REM statements
c. Have the program PRINT "THE VOLUME="; (your answer); "CUBIC IN."
3. Write a program to convert Fahrenheit to Celsius.
a. GIVEN: C = (F - 32) X (5/9) where F = 75°
b. Change the value of F to 45° and RUN the program again.
4. Write a program to convert Celsius to Fahrenheit.
a. GIVEN: F = 9/5 X C + 32 where C = 20°
b. Change the value of C to 35° and RUN the program again.
Note:
O Remember that a formula must be written in proper computer form in your programs,
i.e., A = 1/2*B*H for area of a triangle.
74
I SUMMARY
PKINT and LET
• LET is an optional key word in Tl BASIC.
— Other computers using BASIC might require the use of LET.
• A comma in a PRINT statement tells the computer to leave several spaces
between items separated by the commas.
• A semicolon inserts one space between two items it is separating on the
same line if the two items include a numeric variable and a "message."
Note:
O 1 PRINT "A" tells the computer to print the letter A.
1 PRINT A tells the computer to print the value of the variable A
(a number).
75
14.10
PRINT Zones
Zone 1
14 Spaces
Zone 2
14 Spaces
**LEEDS*MIDDLE
SCHOOLCOMPUTER
• The TI-99/4A output is divided into two PRINT zones.
— Each PRINT zone has 14 spaces for up to 14 characters.
— The TI-99/4A can display up to 28 characters per line
(2 X 14 = 28).
• Commas are used to tell the computer to move to the next PRINT zone.
— The cursor moves to the next PRINT zone each time a comma is
encountered.
Note:
O Try typing in the words shown above. Count each character or symbol as
you type it. Also note that there are no spaces between characters.
76
14,11
PRINT Zones ond the Use of Commos
YOUR ACTION
DISPLAY
1 . Type NEW and press I ENTER
2. Type Line 10 and press I ENTER
3. Type RUN and press I ENTER
BASIC READY
>10 PRINT'ZONE rV'ZONE 2"
>RUN
Z0NE1
** DONE
ZONE 2
(A)
(B)
Note:
® There are two (2) 14-character PRINT zones per line (since 2 X 14 = 28, the screen
can display up to 28 characters per line).
(B) The comma tells the computer to move to the next PRINT zone each time a comma is
encountered in a PRINT statement.
77
14,12
Semicolon versus Commo
YOUR ACTION
DISPLAY
1 . Type NEW and press I ENTER
2. Type Line 1 exactly as shown,
then press I ENTER
3. Type Line 20 exactly as shown,
then press I ENTER
4. Type RUN and press I ENTER
5. Type NEW and press I ENTER
6. Type Lines 30, 40, 50, and 60
as shown.
7. Type RUN and press I ENTER
BASIC READY
>1 PRINT" A":"SEMICOLON";"PAC
KS":"ITEMS":"CLOSE'rTOGETHE
R"
>20 PRINT'BUT A"."COMMA";'LEA
VES";'SPACES"
>RUN
ASEMICOLONPACKSITEMSCLOSE
TOGETHER
BUT A COMMA
LEAVES SPACES
Tl BASIC READY
>30 LET A=5
>40 LETB=10
>50 LET C=1 5
>60 PRINT A:B:C
>RUN
5 10 15
** DONE **
Note:
O On the TI-99/4A, when the semicolon is used between two numeric variables in a
PRINT statement, the computer automatically inserts one space between them. This
might not be true with other computers, so beware!
78
SUfANiAKf
Use of the Semicolon ond Commo
• The effect of the semicolon varies from computer to computer, but it is
always true that a semicolon leaves less space within the output than
a comma.
• GENERAL RULE:
When you want more than one item on the same line and
— if you want your results or output spread out, use a comma
— if you want your results or output closer together, use a semicolon
• EXCEPTION:
A numeric variable will have a space before and after the number when
PRINTed on the TI-99/4A. For example, if your program contained the
following line:
60 PRINT'THE AREA IS";A;"SQ. INCHES"
the output will look like this (if A = 50):
THE AREA IS 50 SQ. INCHES
Notice that there is space before and after the number 50 in the output,
even though the PRINT statement contains semicolons.
^1 PRACTICE 6
Perimeter of o Rectangle Program
Part I
1 . Enter and RUN this program:
10 REM PERIMETER OF A RECTANGLE
20 REM P=2*L+2*W
30 LET L=9
40 LET W=4
50 LET P=2*L+2*W
60 PRINT P
2. Add a new program line to include a label on your answer. For example, THE PERIMETER
OF THE RECTANGLE IS 26 INCHES.
3. Add new program lines to PRINT the following:
a. THE LENGTH OF THE RECTANGLE IS 9 INCHES.
b. THE WIDTH OF THE RECTANGLE IS 4 INCHES.
Part II
1. DonotXype NEW.
2 Change the values of L and W in the program. (Think before you change the lines! How many
lines do you have to change? Change only those lines!)
80
^ I PRACTICE 7
Program Using AAothemoticQl Operators
1 . Enter and RUN this program:
10 REM MATH PROBLEMS
20 LET A=75
30 LET B=50
40 LET C=A+B
50 PRINT C
2. Change the values of A and B in the program and RUN it. Fill in the results: A=
B= C=
3. Add a program line to label the answer. Example: THE SUM IS (your answer).
4. Write a program to multiply (*) two numbers (any two).
5. Add the program line to PRINT: "THE PRODUCT OF" (your no.) "*" (your no.) "IS"
(your answer). Example: THE PRODUCT OF 5*5 IS 25.
6. Write a program to divide (/) two numbers (any two).
7. Add the program line to PRINT: "THE QUOTIENT OF" (your #) "/" (your #) "IS" (your
answer). Example: THE QUOTIENT OF 10/2 IS 5.
8. Write a program to subtract (-) two numbers (any two).
9. Add the program line to PRINT: "THE DIFFERENCE BETWEEN" (your #) "-" (your #) "IS"
(your answer). Example: THE DIFFERENCE BETWEEN 10-5 IS 5.
Additional practices for this part will be found in the back of the book.
81
Scientific Notation
What You Will Learn
To understand and use scientific notation.
Review and Feedback
The purpose of tin is part of tine program is to evaluate students' overall
performance and determine which students are having problems. The
students who are having problems will be given the opportunity to review
concepts they have not mastered. The review and feedback phase is divided
into the following parts:
1 . Exam — written/lab
2. Open discussion with students about their concerns and interests
3. Evaluation of student's performance
4. Recommendations
[5A
Scientific Notation
Scientists often express large numbers like 186,000 and small numbers like
0.00015 as the product of two numbers.
Example:
a. 186,000 = 1.86X105
b. 0.00015 = 1.5 X 10-4
c. 764,000 = 7.64 X 105
d. 0.0347 = 3.47 X 10-2
e. 5,000,000 = 5 X 106
84
Scientific Notation (Cont.)
Ordinary
Notation
Scientific
Notation
Scientific
Notation on
TI-99/4A
50,000,000,000
.00000000003
.0000000000006
1 300000000000000
1 780000000000000
5X10ie»
3X10-11
6X10-13
1.3 X 1015
1.78x1016
5. E+10
3.E-11
6. E-13
1.3E+15
1.78E+16
• The TI-99/4A uses scientific notation for very large and very small numbers.
• Rule 1: E + 13 means move the decimal point 13 places to the right.
• Rule 2: E - 13 means move the decimal point 13 places to the left.
Note:
O Numbers with 11 or more digits are automatically converted to scientific notation on
the TI-99/4A.
85
ASSIGNMENTS-!
1. Enter and RUN the following program:
5 CALL CLEAR
1 LET A = ^mmmmmm
20 LET B = .0000000000123
30 LET C = .00000000017865
40 LET D = yj^wmmmmm
50 PRINT A.B.C.D
2. Experiment with scientific notation until you feel comfortable with it.
86
REVIEW AND FEEDBACK
1. Quiz — written/lab
2. Open discussion with students on concerns and interest
3. Evaluation of students' performance
4. Recommendations
Feedback Questionnoire
1. Do you like working with computers? ^ If not, why not?
2. What things do you like most about computers?
3. What do you dislike most about computers?
4. If you were a design engineer and could design the computer to do any-
thing you wanted it to, what kinds of things would you include in your design?
(Use your imagination!)
5. What was the hardest thing for you to understand about the computer so
far?
6. What was the easiest thing for you to understand?
7. Were you afraid or nervous when you first used the computer?
8. Do you feel comfortable using the computer now? ^^ ^^
9. Would you prefer to be doing something else rather than learning about
computers? —^5-,^ If yes, what would you like to do?
10. Is the teacher going too fast, too slow, or just right for you?
11 . Do you find the lessons interesting, boring, or so-so?
12. If you could teach this course, what would you do to make the lessons
more interesting? —
13. Have you decided what you want to do for a vocation?
If yes, what?
14. Would you like to take additional courses to learn more about computers
and programming?
15. Do you have any additional comments?
^ I PRACTICE 6
Scientific Notation
1 . Convert the following to standard scientific notation (Example: 5,000,000 = 5X106):
a. 7,120,000,000
b. .000007
c. .00000008
d. 6,100,000,000,000
e. 80000000000000000 (16 zeroes)
f. 8000000000000000 (15 zeroes)
g. 913,000,000,000
h. 77,000,000,000,000
i. 409,000,000,000,000
j. 3210000000
2. Change the above numbers to computer scientific notation used in the TI-99/4A.
(Example: 500,000,000,000 = 5.E+11 ).
89
IVelotionol Operators ond
IF-THEN/GOTO Statements
What You Will Learn
1. How computers compare (or relate) one value with another.
2. To explain the purpose and use of the six relational operators: =, >, <,
<=. >=, <>.
3. To explain the purpose and use of the key words IF-THEN, GOTO.
4. To write, enter, and RUN programs that use IF-THEN and GOTO
statements.
5. To understand and use the counting program.
91
[6A
Kelotionol Operators
• Relational operators allow a computer to compare one value with another.
— The three relational operators include:
Symbol
Meaning
Examples
Equals
A = B
>
Greater than
A>B
<
Less than
A<B
Combining the three operators above
we have:
<>
Is not equal to
AOS
Less than or
A<=B
equal to
>=
Greater than or
A>=B
equal to
Note:
O To distinguish between < and >, just remember that the smaller part of
the < symbol points to the smaller of two quantities being compared.
92
IF-THEN (Conditional Drenching)
• IF-THEN is used in conditional branching.
— That is, the program will "branch" to another part of the program on the
condition that it passes the test it contains.
— If the test fails, the program simply continues to the next line.
• Example:
LINE NUMBER
KEY
WORD
CONDITION TO BE TESTED
KEY
WORD
IF "YES" BRANCH TO LINE NO.
20
30
IF
A = 5
THEN
50
IF "NO" NEXT LINE
93
Sample Program Using IF-THEN
• Program:
10 LET A = 5
20 IFA = 5THEN 50
30 PRINT "A DOES NOT EQUAL 5"
40 END
50 PRINT "A EQUALS 5"
RUN
• The screen should display:
A EQUALS 5
• Why is Line 20 a conditional branching statement?
— What's the condition or test?
94
^ I EXERCISE M
IF-THEN
Given: A = 10, B = 20, C = 30
Exercise Condition Is Branch to
(T or F) (Line N)
No.
Statement
1.
10
IF
A = B THEN 40
2.
10
IF
A <> B THEN 50
3.
10
IF
A>BTHEN60
4.
10
IF
A < B THEN 70
5.
10
IF
C <= A + B THEN 80
6.
10
IF
OA + BTHEN90
7.
10
IF
B>ATHEN 100
8.
10
IF
B/A>=C/ATHEN 110
9.
10
IF
A * B <= A * C THEN 120
10.
10
IF
C/A <= A * B THEN 130
20 ®
Note:
® If condition is false (F), the computer will execute the next line (i.e., 20).
95
A Counting Program Using IF-THEN
YOUR ACTION
1. Type in these lines.
2. RUN the program.
DISPLAY
>10LET J=0
>20 LET J=J+1
>30 PRINT J
>40IFJ<10THEN 20
1
2
3
4
5
6
7
8
9
10
^ I EXERCISE 6-2
Modify above program to count to 50 by 5's.
96
IF-THEN Counter Program
10 j=0
20 J = J + 1
30 PRINT J.
40IFJ<4THEN 20
50 END
Program Analysis
Initialize
Program
Execution
'J" Counter
Status
Display
1st Time
2nd Time
3rd Time
4th Time
END
10J =
20 J = J + 1
30 PRINT J,
^40 IF J <4 THEN 20
V20 J = J + 1
30 PRINT J,
^40IFJ<4THEN 20
V20 J = J + 1
30 PRINT J,
^40IFJ<4THEN20
V20 J = J + 1
30 PRINT J
40 IF J <4 THEN 20
50 END
m
[11=0+1
2=1+1
3 =2 + 1
[4] = 3 + 1
1
3
2
4
97
^ I EXERCISE 6-3
GOTO (Unconditionol Drenching)
Type and RUN this program:
10 CALL CLEAR
20 PRINT "YOUR NAME";
30 GOTO 20
What happened?
— Do you know how to stop the program? (What about the IFCTNI and
CLEAR I keys?)
— What does Line 30 tell the computer to do?
— Are there any tests or conditions to be satisfied in Line 30 before it does
what it has to do?
— Do you understand now why the GOTO statement is called an uncondi-
tional branching statement?
98
^ I EXERCISE 6^
GOTO/IF-THEN
Study the program below and write the message that would be
printed if the program were executed.
1 PRINT "WELCOME TO LEEDS MIDDLE SCHOOL"
20 GOTO 60
25 PRINT
30 PRINT "HELLO SUPERSTAR"
35 END
40 PRINT "COMPUTERS ARE MY THING"
50 GOTO 100
60 IFA = 5THEN 140
70 PRINT "COMPUTER WORKSHOP"
80 GOTO 40
90 REM A TRICKY PROGRAM
100 LETA = 5
1 1 GOTO 60
1 20 PRINT "AND I'M A SUPERSTAR!"
1 30 GOTO 25
140 PRINT "TI-99/4A MICROCOMPUTER"
1 50 PRINT "I CAN DO IT TOO"
1 60 PRINT "I SPEAK BASIC"
170 GOTO 120
ASSIGNMENT 6-1
Write a program of your choice using conditional (IF-THEN) and uncondi-
tional (GOTO) statements.
Write a counting program, counting to 100 by 10's.
16.6
What We Hove Learned
• Relational operators: =, >, <, <>, <=, >=
• IF-THEN
• GOTO (no space between GO and TO)
• Conditional branching
— If condition is met (i.e., True), branch to designated line in program.
— If condition is not met (i.e.. False), go to next line number in program.
• Unconditional branching
— GOTO line XX (no conditions or tests required).
— A GOTO statement, as the name implies, forces the computer to go to a
specific statement anywhere in the program.
100
^ I PRACTICE 9~
Using IF-THEN
Part I
1 . Enter and RUN the following program:
10 LET A =10
20 IF A = 10 THEN 50
30 PRINT "A DOES NOT EQUAL 10"
40 END
50 PRINT "A EQUALS 10"
2. Change Line 10 to LET A = 5 and then RUN it.
3. Change Line 10 to LET A = 3 and then RUN it.
Part 11
1 . Write a program that assigns a value to variables A and B and prints either "A IS GREATER
THAN B" or "B IS GREATER THAN A."
2. Change the values of A and B and RUN the program several times.
101
^ I PRACTICE 10
Counting Program Using IF-THEN
1 . Enter and RUN this program:
10 LET J =
20 LET J = J + 1
30 PRINT J
40 IF J < 10 THEN 20
2. Write a program to count from 1 to 15.
3. Write a program to count to 50 by 5's.
4. Write a program to count to 100 by 10's.
5. Write a program to count from 15 to 30 and PRINT the answers in one column (vertically).
Example: 15
16
17
18
and so forth
6. Write a program to count from 20 to 40. PRINT answers horizontally in two columns.
Example:
20 21
22 23
and so forth
102
The INPUT Statement
What You Will Learn
1 . To explain the purpose and use of the key word INPUT.
2. To explain the purpose and use of INPUT with built-in PRINT.
3. To explain the purpose and use of a trailing semicolon in a PRINT
statement.
4. To identify and use string variables.
5. To explain the difference between numeric and string variables.
6. To write, enter, and RUN programs that use the concepts of this lesson.
103
171
Description of the INPUT Stotement
Statement Function
10 INPUT A • Causes the computer to stop, PRINT a ?, and wait for you to type in a
number.
• After you type in a v alue for A , the computer continues the program
when you press the I ENTER I key
104
172
Example of the INPUT Statement
YOUR ACTION
DISPLAY
1. Type NEW and press I ENTER
2. Type and enter Lines 5 and 10 as
shown.
3. Type RUN.
4. Enter a n umber (e.g., type 5 and press
ENTER I ).
5. RUN this program several times to get
the feel of it.
BASIC READY
>5 PRINT "THE NUMBER IS"
>10INPUTA
>RUN
THE NUMBER IS
?■
THE NUMBER IS
?5
** DONE **
>l
(A)
Note:
® The question mark on the screen means, "It's your turn and I'm waiting."
105
17.0
The INPUT Statement with Duilt-ln PRINT
YOUR ACTION
DISPLAY
1. Type NEW and press lENTERI .
2. Type in the program as shown.
3. RUN the program and enter a 5 when
the program stops for the INPUT
4. Type Line 5 to read:
5. RUN the program again; enter a 7
when the program stops for the INPUT
6. Change Line 5 to read:
7. Delete Li ne 10 by typing 10 and
pressing lENTERI .
8. RUN the program and enter a 9 when
the program stops for the INPUT
9. LIST the program and RUN it several
times, entering a different number each
time.
BASIC READY
>5 PRINT "WHAT IS THE NUMBER"
>10INPUTA
>20 PRINT "THE NUMBER WAS":A
>RUN
WHAT IS THE NUMBER
?■
THE NUMBER WAS 5
DONE ^
>5 PRINT "WHAT IS THE NUMBER"
>RUN
WHAT IS THE NUMBER?^
THE NUMBER WAS 7
- DONE **
>5 INPUT "WHAT IS THE NUMBER"
:A
>RUN
WHAT IS THE NUMBER I
THE NUMBER WAS 9
** DONE **
®
1
>LIST
5 INPUT "WHAT IS THE NUMBER"
:A
20 PRINT "THE NUMBER WAS";A
>■
106
Note:
(A) A semicolon in Line 5 puts tlie question mark on tlie same line as the message.
(B) An INPUT statement has a built-in PRINT feature, allowing you to combine a PRINT
with an INPUT for the message you want! The resulting RUN was exactly the same
except the "?" was not generated.
© INPUT with built-in PRINT has the following format:
5 INPUT "WHAT IS THE NUMBER":A
t \ / / \
Line Key Message Colon Variable
Number Word
If you want a question mark (?) at the end of the message, you would make sure it was
the last character before you closed the quotes.
\TA
Area of Rectangle Program
(Using INPUT Statements)
1 REM AREA OF A RECTANGLE
20 REM A = L * W
30 PRINT "THE LENGTH IS"
40 INPUT L
50 PRINT "THE WIDTH IS"
60 INPUT W
70 A = L* W
80 PRINT "THE AREA IS"
90 PRINT A
107
17.5
Area of Rectangle Problem Revisited
(Using INPUT Statements)
YOUR ACTION
1. Type in program Lines 10 through 60 as
shown.
2. Type RUN and press I ENTER
3. Type in t he length (say 10) and press
lENTER
4. Type in the width and press lENTER
5. What is your answer?
DISPLAY
>1 REM AREA OF A RECTANGLE PROBLEM
>20 INPUT "THE LENGTH IS": L
>30 INPUT "THE WIDTH IS": W
>40 A = L * W
>50 PRINT "THE AREA IS":
>60 PRINT A
THE LENGTH IS 10
THE WIDTH IS |
®
(B)
Note:
(A) Note the trailing semicolon. It is used to hook Lines 50 and 60 together.
(B) Note that the pro gram wa its for an input from the keyboard. If you don't enter a
number or press I ENTER I , it will just stay at that line until the machine is turned off
or reset. Also, note that there is no space between the word "IS" and your entry (10). If
you want a space, edit Lines 10 and 20 so that you can insert a space between the word
"IS" and the last quote (").
108
^|ASSIGNJVIENT7-1
• Write a program to do the following (using INPUT statements):
a. INPUT your age
b. INPUT your zip code
c. INPUT your weight
d. INPUT your height in inches
e. PRINT each of the above with the proper labels. For example:
MY AGE IS 15
or
I AM 15 YEARS OLD
109
[76
What We Hove Learned
• A trailing semicolon iiooks two lines togetiier.
• An INPUT statement causes the computer to stop and wait for an input
from the l<eyboard.
• An INPUT statement can have a built-in message to tell you what to enter.
For example:
10 INPUT "YOUR AGE": A
• If you want a question mark (?) to be displayed with your INPUT statement,
you must include it inside the quotes.
• If you want a space between your entry (A) and the last character inside
the quotes, you must leave a space.
For example:
10 INPUT "YOUR AGE? ":A
110
1 77
Numeric versus String Voridbles
Numeric Declaration String
Variable Character'' Variable
A + $ = A$
A1 + $ = A1$
AB + $ = AB$
AZ + $ = AZ$
Note:
® Adding the string declaraton cliaracter ($) to the numeric variable allows
you to use any numeric variable as a string variable.
111
7.6
Example of Use of String Voriobles
YOUR ACTION
DISPLAY
1 . Type and enter.
2. RUN.
>10CALL CLEAR
>20 INPUT "YOUR NAME IS ": AS
>30 PRINT "HELLO THERE, "; A$
YOUR NAME IS ■
HELLO THERE, BILL
«• DONE "
®
Note:
(A) Don't forget to use a colon (:) in Line 20 and a semicolon (;) in Line 30. Also, be sure to
leave a space before closing the quotes in Lines 20 and 30.
(D It will print your name and not "BILL," unless your name is "BILL."
112
^|EXEKCISE7-1
YOUR ACTION
DISPLAY
1 . Type and enter.
2. RUN.
>5 CALL CLEAR
>10 INPUT "YOUR FIRST NAME? ":
A$
>20 INPUT "YOUR MIDDLE NAME? "
:B$
>30 INPUT "YOUR LAST NAME? ":C
$
>40 PRINT A$;" ";B$:" ";C$
>50 INPUT "YOUR FULL NAME? ":D
$
>60 PRINT D$
YOUR FIRST NAME? AUBREY
YOUR MIDDLE NAME? BRIGHT
YOUR LAST NAME? JONES
AUBREY BRIGHT JONES
YOUR FULL NAME? AUBREY BRIGH
T JONES
AUBREY BRIGHT JONES
®
DONE
Note:
(A) String variables can be printed together.
O To insert a space between string variables, you must print a space enclosed in quotes
betv\/een the variables.
O A semicolon alone will not cause a space to be printed between string variables.
113
ASSIGNMENT?^
1. RUN and analyze the following program:
1 INPUT "YOUR NAME IS": A$
20 INPUT "YOUR HOUSE NUMBER": A
30 INPUT "YOUR STREET NAME": B$
40 INPUT "YOUR ZIP CODE" : B
50 PRINT A$
60 PRINT A : B$
70 PRINT "ZIP CODE" ; B
2. Answer the following questions:
a. Why were A$ and B$ (string variables) required in Lines 10 and 30?
b. Why didn't Line 60 contain quotes? (60 PRINT A; " " ; B$)
c. Why didn't we use the $ symbol (or string declaration character) with A
and B in Lines 20 and 40?
SUMlVlAKy
String Voriobles
• string variables can be assigned to indicate letters, words, and/or
combinations of letters, numbers, and special characters.
• It Is possible to contain up to 255 characters per string variable.
• String variables can be printed together.
• In a PRINT statement, use " " marks containing a space between string
variables to separate them.
114
PRACTICE 11
Perimeter of Rectangle Problem
(Using INPUT Statements)
1 . Enter and RUN this program:
10 REM PERIMETER OF RECTANGLE PROBLEM
20 INPUT "WHAT IS THE LENGTH"!
30 INPUT "WHAT IS THE WIDTH":W
40 P = 2*L+2*W
50 PRINT "THE PERIMETER IS";P
2. Write a new program using INPUT statements to find volume (volume = length X width X
height).
3. Include a statement:
THE VOLUME IS
^ I PRACTICE 12
More INPUT Statement Programs
Parti
1 . Write a program using INPUT statements to change meters to centimeters (centimeters = 100
X meters).
2. Include a statement:
METERS EQUALS CENTIMETERS.
Part II
1 . Write a new program using INPUT statements to do the following:
a. INPUT the year you were born.
b. INPUT how many brothers you have.
c. INPUT how many sisters yoy have.
2. PRINT each with the proper labels. Example:
I WAS BORN IN
HAVE BROTHERS.
115
^[PRACTICE 10
String
Parti
1 . Enter and RUN the following program:
1 INPUT "WHAT IS YOUR NAME? ":A$
20 INPUT "WHAT IS YOUR HOUSE NUMBER? ":A
30 INPUT "WHAT IS YOUR STREET NAME? ":B$
40 INPUT "WHAT IS YOUR ZIP CODE? ":B
50 PRINT A$
60 PRINT A;B$
70 PRINT "ZIP CODE";B
2. Answer the following questions:
a. Why are A$ and B$ (string variables) required in Lines 10 and 30?
b. Why didn't we use the $ symbol (or string declaration character) with A and B in Lines 20
and 40?
Part II
1 . Write a new program using INPUT statements, string variables, and a space between each
line. PRINT all information (example: MY BEST FRIEND IS ) to give the following
information:
a. Your best friend.
b. Your favorite subject.
c. Your favorite food.
d. Your favorite movie star.
e. Your favorite color.
f. Your zodiac sign.
116
Using the Colculotor Mode
What You Will Learn
1.
2.
3.
To review the mathematical operators.
To review the order of operations using the l\/I.D.A.S. rule.
How to use the TI-99/4A in the calculator mode using variables.
I REVIEW
Moth Operators
= (Equals) * (Multiply)
+ (Add) / (Divide)
— (Subtract) A (Exponentiation)
Note:
O Exponentiation (A) means raising a number to a power like 22, 2^, or 24.
REVIEW
Order of Arithmetic Operotlons
Multiply -* Divide -* Add -* Subtract (left to right)
— "My Dear Aunt Sally"
If parentheses are used:
— the innermost set of parentheses is simplified first, followed by each
successive set outward.
— the M.D.A.S. order is followed inside all sets of parentheses.
REVIEW
Order of Operations Example
(without Parentheses)
If there are no parentheses, the computer performs operations by going
from left to right doing exponentiation operations (A) first. Then (*) and (/)
are done in order from left to right and finally (+) and (— ) are done in order
from left to right. (Remember M.D.A.S.!)
Example:
4 + 5*4A3-4/2 =
4 + 5* 64 -4/2 =
4 + 320 - 4/2 =
4+ 320 -L2J =
[324] - 2 = [322
118
I REVIEW
Order of Operations Example
(with Parentheses)
If there are parentheses, the computer starts at the inner pair of parentheses
and converts everything to a single number. Then the computer repeats the
process with the next pair of parentheses working "inside" out.
Example:
( (6 + 4) * 2) /4 =
( [101 *2)/4 =
[20l/4 = [5l
Note:
O The same answer can be worked out first on paper and then on the
computer. If you type in
PRINT ( (6+4) * 2) /4
and press lENTERl . the computer will print out 5.
119
m
Colculotor Mode Clmmediote Mode*^')
• Use PRINT followed by a mathematical expression to have the
TI-99/4A act like a calculator.
• You do not use a line number to operate the calculator mode.
• You can use variables in the calculator mode.
• You should type NEW before using variables in the calculator mode. NEW
clears all the values variables may have.
^lASSIGNMENfe^
Type i n each o f the following and record the computer's response after you
press
ENTER
YOU TYPE RESPONSE
PRINT 4+5
PRINT 6*8-3
PRINT 4+5*4
PRINT 7/2*3-1
PRINT 2A4-5
PRINT (24+3)*(40-2Q)
PRINT (30-5)-7+(3*8)
PRINT 4A3-(34-30)A2
120
^ I ASSIGNMENT 6-2
• Type i n each o f the following and record the computer's response after you
press I ENTER
YOU TYPE RESPONSE
NEW
PRINT A
PRINT B
A=5
B=12
C=4
PRINT A+B-C
PRINT C*A-B
PRINT CAA-B
PRINT A*B-B*A
NEW
PRINT A
PRINT B
PRINT C
121
0,2
What We Hove Learned
• The command NEW clears the values of all variables and erases any
program. Numeric variables will then have a value of 0.
• To use the calculator mode, type PRINT followed by a mathematical expres-
sion and press I ENTER I . The answer to the mathematical expression
will then be printed.
Variables can be assigned values in the calculator mode.
You can evaluate expressions using variables in the calculator mode.
The TI-99/4A evaluates expressions in the calculator mode using the
M.D.A.S. rule.
PRACTICE 14
Colculotor Mode
Parti
1 . Use the TI-99/4A in calculator mode to solve the following:
a. 25*8/2
b. (25+6)-7+(2*4)
c. 7/2*5*2A4
Part II
1 . Assign the following values in the calculator mode (remember to type NEW):
a. A=6
b. B=2
c. C=10
d. D=3
2. Use the calculator mode to solve the following with the values from 1:
a. A*B-C+D
b. DAB*A-C
c. (A+D)*CAB
122
Using the Cassette
Recorder
What You Will Learn
1. How to use the cassette as an output device to save information stored in
memory.
2. How to use the cassette as an input device to load information from tape
to memory.
3. To explain and use the commands SAVE, OLD (Load).
4. To make critical settings on the tape recorder and to practice using the
recorder.
123
m
The Cassette Recorder os on I/O Device
• The cassette tape recorder is an input/output (I/O) device that allows you
to "save" information on cassette or "load" information from cassette.
— When you have typed a long program and wish to save it, you can save
(SAVE) it on cassette.
— When you are ready to use it again, you can load (OLD) it from the
cassette.
— After you have saved your program, you should check it for recording
errors. You can do this with a Check Tape option.
Note:
O You can save only your program on cassette (not the program output).
O Refer to the Tl User's Reference Guide for tips on using the recorder.
124
19,2
SAVE Command (with Check Tope Option)
• Writes (outputs) a copy of the current program from memory to the tape
cassette recorder.
• Format: SAVE <space> file name
— Where "file name" will be either a "CS1" or CS2" (without quotes).
— Where "CS1 " selects cassette #1 and "CS2" selects cassette #2.
• Example:
Command Meaning
SAVE CS1 Write (save) current program on Cassette #1 .
SAVE CS2 Write (save) current program on Cassette #2.
Screen Prompt Meaning
CHECK TAPE (Y OR N) When this message (prompt) occurs during a SAVE processing,
the computer is asking you if you wish to verify that the data
saved is correct. Your response should be: Y (yes). (You do
have the option of typing N, however.) Y or N must be in upper
case.
• If you wish to verify that the recording made by the SAVE command is
accurate, you can let the computer check your tape to make sure your tape
is recorded properly. It is highly recommended that you verify all data.
— To verify, the computer reads and compares the program and tape with
the program in memory.
125
19.0
Saving o Program from Memory
on the Cossette Recorder (Using the
Recorder os on Output Device)
YOUR ACTION
DISPLAY
1. Type and [ENTER I the program shown
2. Place a blank tape in recorder.
3. Rewind tape to the beginning.
4. Type SAVE command as shown.
5. Press I ENTER
6. If tape is rewound, then press
ENTER
7. Press RE CORD and then press
I ENTER I .
8. Type Y (upper-case "Y") for Yes
9. Press I ENTER
10. Press ENTER
1 1 . Press STOP and ENTER
>1 PRINT "THIS IS A TEST PRO
GRAM"
>20 PRINT "THIS PROGRAM WILL
BE SAVED ONTO TAPE."
>SAVE CS1
* REWIND CASSETTE TAPE
THEN PRESS ENTER
* PRESS CASSETTE RECORD
THEN PRESS ENTER
* RECORDING
* PRESS CASSETTE STOP
THEN PRESS ENTER
' CHECK TAPE (Y OR N)? Y
' REWIND CASSETTE TAPE
THEN PRESS ENTER
* PRESS CASSETTE PLAY
THEN PRESS ENTER
* CHECKING
* DATA OK
* PRESS CASSETTE STOP
THEN PRESS ENTER
>■
CS1
CS1
CS1
CS1
CS1
CS1
126
9.4
OLD (Load) Command
• Loads (inputs) a previously saved program from tape to memory.
• Format: OLD file name
— Where "file name" must be CS1, since you can use only CS1 to load
data. However, either CS1 or CS2 can be used to SAVE data.
• Example;
Command Meaning
OLD <space> CS1 Load program previously saved on cassette #1 into memory.
19.5
Loading o Program from Tope Cassette
to Memory (Using the Tope Cassette
OS on Input Device)
YOUR ACTION
DISPLAY
1 . Make certain that the tape is rewound to
the beginning, and also that you type
NEW.
2. Type the command shown.
3. Press the [ENTER I key.
4. Press PLAY on the cassette,
then press I ENTER
5. Press STO P on the cassette,
then press I ENTER .
>NEW
Tl BASIC READY
>OLD CS1
* REWIND CASSETTE TAPE
THEN PRESS ENTER
* PRESS CASSETTE PLAY
THEN PRESS ENTER
* READING
* DATA GK
* PRESS CASSETTE STOP
THEN PRESS ENTER
>■
CS1
CS1
CS1
Note:
O After you type the OLD command and press I ENTER I , the computer will begin
printing instructions on the screen to help you through the procedure.
128
\M I
Loading o Program from Tope Recorder to
Memory (Error Procedure)
• If the computer did not successfully read your program into memory, an error will occur
and you may choose either of these options:
YOUR ACTION
1. Press upper-case R to repeat the
reading procedure.
2. Press upper-case E to exit from the
reading procedure.
Note:
O Before repeating, check the cassette to make certain it is connected in accordance with
the directions given in the User's Reference Guide. Pages 1-9 through 1-12 and page 42
cover this topic.
DISPLAY
ERROR - NO DATA FOUND
PRESS R TO READ
PRESS E TO EXIT
I/O ERROR 56
129
PRACTICE 15
Using the Computer to Solve Problems
1 . Write a program to solve the following problem. Include a PRINT statement in your program
to describe your answer (output).
The total enrollment at Armstrong High School is 1,264. There are 367 freshmen,
322 sophomores, and 298 juniors. How many seniors are there?
2. Write a new program using INPUT statements to solve the same problem.
(That is, you should use an INPUT statement for the total enrollment, number of freshmen,
number of sophomores, number of juniors.)
^ I PRACTICE 16
Finding the Averoge Problems
1 . Write a program to solve the following problem. Include a PRINT statement in your program
to describe your answer.
The weights of three boys are 140 lb., 150 lb., and 130 lb. What is their average weight?
2. Write a new program using INPUT statements to solve the same problem.
(That is, you should use an INPUT statement for the weight of each of the three boys.)
PRACTICE 17
Using the Computer to Solve Problems
1 . Write two programs to solve the following problems. Label your answers.
2. Over a period of six years Mr. Smith drove his car 53,862 miles. What was the average
distance each year?
3. After 12 dozen bulbs were sold, how many of the 1000 bulbs were left?
130
Statements
Using FOR-NEXT...STEP
What You Will Learn
1. To explain the purpose and use of key words FOR-NEXT...STEP.
2. To explain the purpose and use of the terms increment, decrement,
initialize.
3. To compare key words GOTO, IF-THEN, FOR-NEXT and explain how they
relate to one another.
4. To explain the purpose and use of timer loops.
131
1 10,1
FOR-NEXT Statement
Allows the computer to do the same thing over and over a number of
times (and do it very fast!)
YOUR ACTION
DISPLAY
1. Type and enter program as shown.
>5 CALL CLEAR
FOR J = 1 TO 10
PRINT " AUBREY": J
NEXT J
2. Type RUN and press [ENTER
AUBREY 1
AUBREY 2
AUBREY 3
AUBREY 4
AUBREY 5
AUBREY 6
AUBREY 7
AUBREY 8
AUBREY 9
AUBREY 10
** DONE **
>l
132
H0.2
FOR-NEXT...STEP Loop
YOUR ACTION
DISPLAY
1 . Retype and enter Line 10 of resident
program as shown, (a)
2. Type RUN and press I ENTER .
r.
>10FORJ = 1TO10STEP3
AUBREY 1
AUBREY 4
AUBREY 7
AUBREY 10
** DONE **
>l
Note:
® Resident means program currently in memory.
(B) If "STEP" is not included in the statement, an increment of 1 is assigned by the
computer (i.e., STEP 1).
133
110.0
Example of Program Statements
Using FOR-NEXT...STEP
10 \ FOR J = 10 TO 1 STEP -1
20 I PRINT J;
30 J NEXT J
RUN
DISPLAY READS:
10 987654321
134
110.4
Analysis of FOR-NEXT...STEP Statements
LINE
KEY
COUNTER
INITIAL
FINAL
INCREMENT/
NO.
WORD
VARIABLE
VALUE
VALUE
DECREMENT
10
FOR
J
10
TO 1
STEP -1
20 PRINT J;
30 NEXT J
• The FOR-N EXT... STEP loop works as follows: The first time the FOR
statement is executed, the counter is set for the initial value "10." Then it
executes Line 20 (PRINT J). When the program reaches Line 30 (NEXT J),
the counter is decremented by the amount specified (STEP —1). If this
step has a positive value, the counter is incremented by the amount
specified (e.g., STEP 2 means increment by 2's).
135
110,5
Comparison of Program Loops (Listings)
A. GOTO
(Unconditional Loop)
5 CALL CLEAR
10 LET J =
20 LET J = J + 1
30 PRINT "AUBREY" ; J
40 GOTO 20
This program loops
forever (or until you
stop it).
B. IF-THEN
(Conditional Loop)
5 CALL CLEAR
10 LET J =
20J=J+1
30 IFJ>6THEN 99
40 PRINT "AUBREY" ; J
50 GOTO 20
99 END
This program loops
6 times.
C. FOR-NEXT
(Conditional Loop)
5 CALL CLEAR
10FORJ = 1 TO 6
20 PRINT "AUBREY" ; J
30 NEXT J
99 END
This program loops
6 times.
136
110,6
Comparison of Program Loops (Outputs)
A. "DUMB LOOP"^
AUBREY
1
AUBREY
2
AUBREY
3
AUBREY
4
AUBREY
5
AUBREY
6
AUBREY
7
AUBREY
8
AUBREY
9
AUBREY
10
AUBREY
11
AUBREY
12
AUBREY
13
AUBREY
14
AUBREY
15
AUBREY
16
B. "SMART LOOP"
AUBREY 1
AUBREY 2
AUBREY 3
AUBREY 4
AUBREY 5
AUBREY 6
0. "SMART LOOP"
AUBREY 1
AUBREY 2
AUBREY 3
AUBREY 4
AUBREY 5
AUBREY 6
Note:
© Press the IFCTN|[CLEAR| keys to get out of this loop.
137
ISUMiVlARY
FOK-NEXT...STEP
• FOR-NEXT is always used as a pair.
• If the key word "STEP" is not used, the increment of 1 is assumed.
• If the STEP has a negative value, the counter is decremented. For example:
20 FOR J = 10 TO 1 STEP-1
• If the STEP has a positive value, the counter is incremented. For example:
20 FOR J = 4 TO 10 STEP 2
138
no J
Flowchart Symbols
Q ^ Begin or End
ri
Processing Block
Decision Diamond
Output
i
► Connector Arrows
139
H0.6
GOTO Loop
40
GOTO 20
CALL CLEAR
J
10
LET J =
T
20
LET J = J + 1
30 PRINT
"AUBREY" ; J
(Loop)
Clears Screen
Initializes Counter
Counter
Output
140
110.9
IF-THEN Loop
Clears Screen / call clear
Initializes Counter
Counter
Decision Block
T
10
LET J =
20
J = J + 1
(Loop)
50
GOTO 20
NO /30 PRINT
' "AUBREY"; J
Output
99
END
141
FOR-NEXT Loop
Clears Screen / call clear
Counter
Decision Blocl<
10
FOR J = 1 TO 6
—
30
(Loop)
NEXT J
ISJ>6 X NO ^ / 20 PRINT
"AUBREY" ; J
Output
Note:
O FOR-NEXT work together as a counter
142
1 10.11
Timer Loop
• The TI-99/4A can do approximately 330 FOR-NEXT loops
per second.
• Example:
5 REM 10 SECOND TIMER PROGRAM
10 PRINT "TIMER PROGRAM COUNTING"
20 FOR X = 1 TO 3300
30 NEXT X
40 PRINT "TIMER PROGRAM ENDED"
• You don't believe the TI-99/4A can count? Well, try it! Type in the
above program and RUN. Don't forget to use your watch!
ASSIGNMENT 10-1
1. Type in and RUN the following program:
5 CALL CLEAR
1 PRINT "INPUT A VALUE FOR N"
12 PRINT
1 5 INPUT "ENTER 1 500, 2500. 3500 OR 7500":N
20 CALL CLEAR
25 PRINT "THIS IS A DEMONSTRATION OF"
30 PRINT
35 FOR J=1 TO N
37 NEXT N
40 PRINT "USING A FOR-NEXT TIMER LOOP"
45 PRINT
47 PRINT
50 FOR J=1 TO N
55 NEXT J
60 PRINT "IF YOU WISH TO CHANGE THE DISPLAY'S SPEED"
65 PRINT
67 PRINT
70 FOR J=1 TO N
75 NEXT J
80 PRINT "CHANGE THE VALUES OF N IN THE FOR-NEXT LOOP"
85 PRINT
87 PRINT
90 FOR J=1 TO N
95 NEXT J
1 00 PRINT "IF YOU WISH TO STOP THIS DISPLAY"
105 PRINT
107 PRINT
1 1 FOR J=1 TO N
115 NEXT J
120 PRINT "PRESS THE 'FCTN' and 'CLEAR' KEYS"
130 F0RJ=1 TON
135 NEXT J
140 GOTO 20
2. Make certain that you understand this program and can explain it to
your teacher.
144
PRACTICE 16
Counting Programs Using
IF-THEN and FOR-NEXT
1 . Using IF-THEN, write a program to count by 5's from 50 to 5.
a. Written vertically
b. Written horizontally
2. Do not type NEW (that is, SAVE the program above).
3. Using FOR-NEXT, write a program to count by 5's from 50 to 5 written horizontally.
Note: Start your second program at Line 100. That is, type Line 100 as follows: 100 PRINT.
(Of course, this is to insert one space between your outputs.)
4. How many program lines (excluding Line 100) did it take using FOR-NEXT?
How many using IF-THEN?
5. What can you conclude from this task?
M LPRACTICE 19
Using IF-THEK and FOR-NEXT Statements
1 . Using IF-THEN, write a program to generate all the even numbers between 11 and 51 from
the smallest to the largest (that is, 12, 14, 16, and so forth).
2. Do not type NEW.
3. Using FOR-NEXT, write a program that generates the same numbers and PRINT them
horizontally. (Note: Start at Line 100. Type Line 100 as ^ 100 PRINT.)
4. Type NEW and enter.
5. Using IF-THEN, write a program to generate all even numbers between 11 and 51 from the
largest to the smallest.
6. Do the same using FOR-NEXT
145
Keoding Doto
What You Will Learn
1. To explain the purpose and use of the key words READ, DATA, RESTORE.
2. To compare the three different ways you have learned to enter data into
the TI-99/4A.
3. To write, enter, and RUN programs using READ-DATA and RESTORE.
ISA
READ-DATA Statements
READ-DATA statements are much more efficient tlian
INPUT or LET statements wlien you liave lots of data
to enter.
• Explain that the READ-DATA statement pair
is just another way to enter data into the
computer.
112
Ways of Entering Doto into thie Computer
Built-in
10 LET A = 5
• Builds value into the
program
From Keyboard
10 INPUT A
Allows you to enter data
through the keyboard
READ-DATA
Combination
10 DATA 5
20 READ A
DATA statement
contains the value
READ statement assigns
the value to the variable
named
Note:
O Data lines can be read only by READ statements.
O READ-DATA work together to enter data into the computer.
148
mo
READ-DATA Example
5 REM READ— DATA EXAMPLE
DATA statement 10 DATA
READ Statement 20 READ
PRINT Statement 30 PRINT
Note:
O Each variable in a READ statement must have a corresponding value in a DATA
statement.
O Each READ statement can read a number of pieces of data if each variable is separated
by a comma.
O Data lines can be used only by READ statements.
149
^ I EXERCISE iTT
READ-DATA
YOUR ACTION
1 . Type and enter.
2. Type RUN and press I ENTER
DISPLAY
10 DATA 1.2.3.4,5
20 READ A,B.C.D.E
30 PRINT A.B,C.D.E
3
5
Note:
O The display shows that all five pieces of data in Line 10 were read by Line 20, assigned
letters A through E, and printed by Line 30.
O Data lines are always read left to right by READ statements.
150
I SUMMARY
DATA Statement
• Key word that lets you store data inside your program to be accessed
(read) by READ statements.
— Data items will be read sequentially starting with the first item in the first
DATA statement and ending with the last item in the last DATA statement.
— items in data list may be string or numeric values.
— If string values include leading blanks, colons, or commas, you must
enclose these values in quotes.
— DATA statements must match up with the variable types in the corres-
ponding READ statement.
— DATA statements may appear anywhere it is convenient in a program.
• Example:
1 DATA "JONES. A.B."."SMITH, R.J."
20 DATA LEEDS MIDDLE SCHOOL. COMPUTERS
30 DATA 125. 250. 750. 1000
Note:
O Quotes are used in Line 10 because data contain commas.
151
I SUMMARY
READ Stotement
• Key word that instructs the computer to read a value from a DATA state-
ment and assign that value to the specified variable.
— The first time a READ statement is executed, the first value in the first
DATA statement is used; the second time, the second value in the DATA
statement is used. When all the items in the first DATA statement are
used (read), the next READ will use the first value in the second DATA
statement, and so on.
— A DATA ERROR occurs if there are more attempts to READ than there
are data items.
• Example:
10 DATA "JONES, A.B.","SMITH, R.J."
20 DATA LEEDS MIDDLE SCHODL.COMPUTERS
30 DATA 125,250.750.1000
40 READ A$,B$,C$.D$,A,B,C,D
Note:
O There are eight variables in the READ statement and eight items in the
DATA statements.
152
^ I ASSIGNMENT 11-1
1. Type and enter the following program:
5 CALL CLEAR
10 PRINT "NAME'V'GRADE"
20 READ A$
30 IF A$="END" THEN 99
40 READ G
50 IF G > 75 THEN 20
55 PRINT A$.G
60 GOTO 20
70 DATA "GRAY.BiLL".95."J0NESAB.".65
80 DATA "JGNESAC",100."SIVIITH.R.L".70
90 DATA "EPPS.S.W.".60."WELLS.DAVE".100.END
99 PRINT "END OF LIST"
100 END
2. Predict the output of the program.
3. Why were quotes used in the DATA statements?
4. RUN the program and record the results.
153
111.4
RESTORE
• Key word that causes the next READ statement executed to start over with
the first DATA statement.
— This lets your program reuse the same data lines.
— Sometimes it is necessary to READ the same data more than once
without having to RUN the complete program again; therefore,
RESTORE is used.
— Whenever the program comes to RESTORE, all data lines are restored
to their original unread condition, both those lines that have been used
and those that have not been used. This allows all data to be available
for reading again, starting with the first data item in the first data line.
Note:
O Remember that each piece of data in a data line can be read only once
each time the program is RUN. The next time a READ statement requests
a piece of data, it will READ the next piece of data in the data line, or, if
data on that line are all used up, it will go to the next data line and start
reading it. Therefore, the RESTORE statement is needed if the same data
is to be used more than once in the same program.
154
H15
lllustrotion of the RESTORE Statement
10DATA®.2. a 4.5
20... i F0RN = 1T0 5
30 READ A
40 PRINT A;
45 RESTORE
50 NEXT N
RUN
11111
Note:
O RESTORE caused data Line 10 to be restored to its original unread con-
dition, making all data available for reading again.
O Since there is only one READ variable, A, it starts with the first piece of
data, 1 in this case.
155
^ I EXERCISE 11-2
RESTORE ond READ-DATA Statements
in Q FOR-NEXT Loop
YOUR ACTION
1 . Type and enter.
2. Type RUN and press [ENTER
3. Insert Line 45 (type and enter).
4. LIST the program.
5. Type RUN and press [ENTER
DISPLAY
>10DATA 1,2.3,4.5
>20 FOR N = 1 TO 5
>30 READ A
>40 PRINT A ;
>50 NEXT N
r
1 2 3 4 5
- DONE **
>45 RESTORE
>LIST
10 DATA 1.2.3.4.5
20 FOR N = 1 TO 5
30 READ A
40 PRINT A ;
45 RESTORE
50 NEXT N
>RUN
11111
** DONE **
1
Note:
® This restores data line to its original unread condition.
(D Computer reads first data item over and over.
156
iSUiVUVlARY
READ-DATA, RESTORE
• READ-DATA
— These key words are used to enter lots of data into the computer.
— READ-DATA statements are common in programs.
• READ
— Each variable in a READ statement must have a corresponding value in
a DATA statement or a DATA ERROR will occur.
• DATA
— DATA statements can be placed anywhere in a program.
— DATA statements can be used only by READ statements.
— If more than one piece of data is placed in a DATA statement, they must
be separated by commas.
— DATA statements are read from left to right by READ statements.
• RESTORE
— This key word is used to return DATA statements to their original,
unread state so they can be used again.
157
PRACTICE 20
READ-DATA
1 . Type and enter the following program:
5 CALL CLEAR
10 PRINT "NAMEV'GRADE"
20 READ AS
30 IF A$="END" THEN 99
40 READ G
50 IF G < 75 THEN 20
55 PRINT A$,G
60 GOTO 20
70 DATA "GRAY.BILL", 95,"J0NES, A.B.",65
80 DATA "JONES.A.C.".100."SMITH,R.L".70
90 DATA "EPPS. S.W.",60,"WELLS, DAVE",100,END
99 PRINT "END OF LIST"
100 END
2. Predict the output of the program.
3. Why were quotes used in the DATA statements?
4. RUN the program and record the results.
158
Video Display Graphics
What You Will Learn
1. To explain the purpose and use of key words CALL HCHAR, CALL
VCHAR, CALL CHAR, and TAB
2. To become familiar with the layout of the TI-99/4A display via the video
display worl<sheet.
3. To draw pictures and letters on the screen.
4. To write, enter, and RUN programs utilizing all the concepts learned in this
lesson.
O The TI-99/4A provides the user with an unlimited number of possibilities
for graphic application. You should experiment with graphics. This lesson
will introduce you to some of the basic concepts and features used on the
TI-99/4A, but we will only "scratch the surface." You will find out by
experimenting what other kinds of things can be done with graphics on
the TI-99/4A.
O This lesson assumes a black-and-white monitor is used. If you are using a
color monitor, refer to the TI-99/4A User's Reference Guide for additional
information.
Note:
159
112.1
Video Display Layout
32 COLUMNS
24
ROWS
1
I i
!
J
J
1
\
—
s
T
OH
\A
A
C
T
El
R POSITION (1/32 OF ROW
i i [ rr; i - ; r^i"^
1)-
t9Kin CHAR
tACTER POSITION
1 _
-4—
—
1
H
t-
— 1
h
H-
[-,
—
^ -4 1-
1 ;
' — r ■--
1
7
68TH(
[CHARACTER POSITIO
1
\
r
-4-
r
M-
• The display has 768 character positions arranged as 24 rows, with 32
characters per row (24 X 32 = 768 characters).
— One-thirty-second of each display line is a character position.
— Each character position is an 8x8 dot matrix (dot block) which is used
to make characters (see next page).
— Some display screens may not show the two leftmost and two right-
most characters; therefore, your graphics may be more satisfactory if
you use Columns 3-30 and ignore Columns 1 and 2 on the left and 31
and 32 on the right.
160
Illustration of Dot Matrix
for One Character Position
8X8 DOT MATRIX
■;>;
Ir
-.,
s
,-.
1
IS
1
MAGNIFIED VIEW OF ONE
CHARACTER POSITION
24 X 32 = 768 CHARACTER POSITIONS
Note:
O There are 64 dots (maximum) available in a single character position. That
is, one character position = 8x8 = 64 dots (maximum) are available for
generating a single character.
161
112.0
Description of Video Disploy Worifsheet
COLUMNS ►
|l|2|3|4|5|6|7[8| 9 1 10 |l1 |l2 |13 1 14 1 15 |l6 1 17| 18| 19 120| 21 1 22[ 23| 24| 25|26 1 27| 28| 29|30| 2^\i2\
ROWS
■
/
/
A
■
Row 10, Col 14
Row 19, Col 20
• Think of the video display as a grid of square blocks consisting of 32
columns and 24 rows.
— Each square on the grid is identified or located by two values called
coordinates (Row, Column).
— For example, the coordinates 10,14 mean the tenth row and the
fourteenth column.
162
Video Display Worl^sheet for Graphics
COLUMNS ^
I 1 I 2| 3[ 4 I 5| 6| 7| 8| 9 1 10 111 [12 113 |14|1S|16 1 17| 18|19 120| 2l| 22[ 23| 24| 25[26| 27| 28| 29|30| 31|32"]
ROWS
2
T
T
_5_
6_
_7_
J_
9^
10
11
13
14
15
16
17^
18
19
20
II
22
23
24
163
^LEXERCISE 12-1
Using the Video Display Worteheet
• Locate the following X(Row), Y(Col) coordinates on your worksheet and
place an "*" (asterisk) in each location:
Row,Col Row,Col Row,Col Row,Col
4,5
5,5
13,6 4,14
4,6
6,5
13,7 5,14
4,7
7,5
13,8 6,14
4,8
8,5
13,9 7,14
4,9
9,5
13,10 8,14
4,10
10,5
13,11 9,14
4,11
11,5
13,12 10,14
4,12
12,5
13,13 11,14
4,13
13,5
13,14 12,14
Note:
O Your
results should be a 10 X 10 square as shown below:
COLUMNS -
I 1 I 2| 3| 4 I 5| 6| 7| 8| 9 1 10 |11 112 1 13 1 14 1 15 116 1 17| 18| 19 1 20| 21 1 22| 23| 24| 25|26 1 27| 28| 29|30| 3l|32 1
ROWS
164
112,5 I
Tl Graphics Statements
• A special set of statements is used to provide color, graphics, sound,
and other capabilities not usually found in the BASIC programming
language. Whenever you want to use one of these statements, you CALL
for it by name and supply a few specifications. The statement then takes
over and performs its task. You have already used one of these state-
ments, CALL CLEAR in earlier lessons. The format of statements covered
in this lesson are:
— CALL HCHAR (Row, Column, Char Code, Repetitions)
— CALL VCHAR (Row, Column, Char Code, Repetitions)
— CALL CHAR (Char Code, Pattern-Identifier)
112.6
CALL HCHAR (Horizontal Character)
• Displays a character anywhere on the screen and, optionally, repeats it
horizontally.
• Format: CALL HCHAR (Row, Column, Char Code, Repetitions)
— Where "Row" is the starting row number on the screen. The value for
row number can be from 1-24, inclusive.
— "Column" is the starting column number on the screen. The value for
column number can be from 1-32, inclusive.
— "Char Code" or character code is a unique code for any one of the 26
letters of the alphabet, the numbers 0-9, and certain other symbols,
such as the asterisk (*), the plus and minus signs (+ and — ), and the
slash (/). The range for char code can be specified from 0-32767,
inclusive, but the computer will convert the value specified to a range
of 0-225. (Refer to Section 12.8.)
165
— "Repetitions" or number of repetitions is optional. It determines the
number of times you want a character to be repeated horizontafly on
the screen. The range for the number of repetitions is from 0-32767,
inclusive.
Example:
CALL HCHAR (12,
t
space
Row 12
10,
65,
Col 10
Code for
Character "A"
15)
i
Repeat
15 times
COLUMNS ►
I 5 I 6 I 7 | 8 I 9|10|11|12|13|14|15|16|17|18|19|20[21|22|23|24|25|26|27|28|29|30|31|32|
ROWS
T
z_
J_
i_
9_
10^
13
14^
1?
16
17^
18
ii
20
21
22
23
24
166
112.7
CALL VCHAR (Vertical Character)
• Displays a character anywhere on the screen and, optionally, repeats it
vertically. The computer will display the character beginning at the
specified row and column. If the character is to be repeated, it will
continue down the screen.
• Format: CALL VCHAR (Row, Column, Char Code, Repetitions)
— Where "Row," "Column," "Char Code," and "Repetitions" have the
same meaning as for CALL HCHAR.
• Example:
12, 66,
CALL VCHAR (15,
t
space
Row 15
Col 12
10)
i
Repeat
10 times
Code for
Character "B"
COLUMNS ►
l|2|3|4|5|6|7|e| 9|10|11|12|13|14|15|16|17|18|19|Z0|21|22|23|24|?5|?6[27|28|2»|30|31|32|
ROWS
B
B
B
B
B
B
B
B
B
B
167
112,6
Character Codes
• All characters that print on the screen (letters, numbers, and symt)ols)
are Identified by numeric character codes. The standard characters are
represented by character codes 32-127. There are 32 additional codes
(128-159) available for use in defining special characters for graphics
programs. These codes are shown below:
>ode
Char
Code
Char
Code Char
32
(space)
71
G
112 p
33
!
(exclamation point)
72
H
113 Q
34
(quote)
73
1
114 R
35
#
(number or pound sign)
74
J
115 s
36
$
(dollar)
75
K
116 T
37
%
(percent)
76
L
117 u
38
&
(ampersand)
77
M
118 V
39
(apostrophe)
78
N
119 w
40
(
(open parenthesis)
79
120 X
41
)
(close parenthesis)
80
P
121 Y
42
*
(asterisk)
81
Q
122 z
43
+
(plus)
82
R
123 { (left brace)
44
(comma)
83
S
124 :
45
—
(minus)
84
T
125 } (right brace)
46
(period)
85
U
126 ~ (tilde)
47
/
(slant)
86
V
127 DEL (appears on
48
87
w
screen as a
49
1
88
X
blank)
50
2
89
Y
128-159 (user-defined)
51
3
90
z
52
4
91
[
(open bracket)
53
5
92
\
(reverse slant)
54
6
93
]
(close bracket)
55
7
94
A
(exponentiation)
56
8
95
(line)
57
9
96
N
(grave)
58
(colon)
97
A
59
(semicolon)
98
B
60
<
(less than)
99
C
61
(equals)
100
D
62
>
(greater than)
101
E
63
?
(question mark)
102
F
64
@
(at sign)
103
G
65
A
104
H
66
B
105
1
67
C
106
J
68
D
107
K
69
E
108
L
70
F
109
M
110
N
111
168
^IEXEKCISE12-2
Using the Statements HCHAR and VCHAR
(Drowing o 10 X 10 Square)
YOUR ACTION
DISPLAY
1 . Type NEW and enter the program
as shown.
2. RUN the program several times.
3. Type program lines shown ( do not
type NEW).
4. Before you RUN the program with
these lines added, write what you
expect to see.
5. RUN the program.
6. Explain what happened and why.
7. LIST your program and make certain
you understood it.
>10CALL CLEAR
>20 CALL HCHAR (14.5.42.10]
>30 CALL VCHAR CI 5.5.42.9)
>40 CALL HCHAR (23.B.42.9)
>50 CALL VCHAR (14.14.42.9)
>25 FOR DELAY = 1 TO 500
>27 NEXT DELAY
>35 FOR DELAY = 1 TO 500
>37 NEXT DELAY
>45 FOR DELAY = 1 TO 500
>47 NEXT DELAY
Note:
O Line 20 displays an (code 42) starting at Row 14, Col 5 and repeats it 10 times
horizontally across Row 14.
169
Line 30 displays an starting at Row 15, Col 5 and repeats it 9 times vertically down
Col 5.
Line 40 displays an starting at Row 23, Col 6 and repeats it 9 times horizontally
across Row 23.
Line 50 displays an starting at Row 14, Col 14 and repeats it 9 times vertically down
Col 14.
EXERCISE 12-3
''Floshy'' Characters
YOUR ACTION
DISPLAY
1. Type NEW and enter the program
shown.
RUN the program (press I FCTN I and
CLEAR I to stop).
>10CALL CLEAR
>20 CALL HCHAR (1 3.1 0.1 04]
>30 CALL HCHAR (1 3.1 1 .1 01 ]
>40 CALL HCHAR (1 3.1 2,1 08)
>50 CALL HCHAR (1 3.1 3.1 08]
>60 CALL HCHAR (1 3.1 4.1 1 1 ]
>70 FOR D = 1 TO 300
>80 NEXT D
>90 CALL CLEAR
>100 FOR = 1 TO 200
>110NEXTD
>120 GOTO 20
HELLO
t
(flashing]
Note:
O Line 20 displays an "H" (code 104) at Row 13, Col 10.
170
Line 30 displays an "E" (code 101) at Row 13, Colli.
Line 40 displays an "L" (code 108) at Row 13, Col 12.
Line 50 displays an "L" (code 108) at Row 13, Col 13.
Line 60 displays an "O" (code 111) at Row 13, Col 14.
Lines 70 and 80 cause the program to pause after printing.
Line 90 clears the screen.
Lines 100 and 110 delay the program after clearing.
Line 120 repeats the process.
O The program above shows one way to create a flashing graphic. The steps are very
simple:
1 . Print the character (Lines 20-60).
2. Delay the program (Lines 70 and 80).
3. Clear the screen (Line 90).
4. Delay the program again (Lines 100 and 110).
5. Repeat the process (Line 120).
171
1 12.9
CALL CHAR Statement
• Allows you to define or create your own special graphic characters. (A
standard set of character codes 32-127 has already been defined in
Section 12.8.)
— Also allows you to establish additional characters using codes
128-159. These codes are identified as "user-defined" characters.
• Format: CALL CHAR (Char Code, Pattern-Identifier)
— Where "Char Code" specifies the code of the character you wish to
define and must be a value between 32 and 159, inclusive.
— The "Pattern-Identifier" is a 16-character string expression that
specifies the pattern of the character you want to use in your program.
This string expression is a coded representation of the 64 dots that
make up a character position on the screen. These 64 dots comprise
an 8 X 8 grid or dot matrix as shown on the next page greatly
enlarged.
— To create a character, you must tell the computer which of the 64 dots
of the 8 X 8 matrix to turn on and which to leave off. You do this only
when you are creating nonstandard or new characters. Standard
characters (A-Z and 0-9) are automatically programmed so that the
computer turns on the appropriate dots to produce the desired
images.
• Example
CALL CHAR (128, "FFFFFFFFFFFFFFFF")
space I
Character code
you are defining
16-character
string expression
Note:
O Character code 128 is defined in this statement as a lighted dot by using
the string expression "FFFFFFFFFFFFFFFF," which happens to be a
shorthand code for turning all dots on.
172
1 12,10
Illustration of Dot Motrix for
Two Choracter Positions
24
ROWS
32 COLUMNS
/8X8 DC
3T MATRi:
MAGNIFIED VIEW OF ONE
CHARACTER POSITION
WITH ALL DOTS
"OFF" (INVISIBLE)
8X8 DOT MATRIX
}
MAGNIFIED VIEW OF ONE
CHARACTER POSITION
WITH ALL DOTS "ON"
Note:
O The character code for turning all dots "on" is "FFFFFFFFFFFFFFFF"
or
CALL CHAR(128,"FFFFFFFFFFFFFFFF")
173
EXERCISE 12-4
Large-Size Letters with TI-99/4A
COLUMNS-
J 1 I 2| 3| 4 I 5| 6| 7| 8| 9|l0|ll|l2|l3|l4|l5|16|l7|l8|l9|20|2l|22|23|24|25|26[27[F8t
ROWS
I I I I I I I I I I I I I I I I I i n □
YOUR ACTION
1 . Type NEW and enter the program
shown.
DISPLAY
>10CALL CLEAR
>20 CALL CHAR(128.TFFFFFFFFF
FFFFFF"]
>30 CALL HCHAR(4.5,128.6]
>40 CALL VCHAR(5.5.128.6)
>50 CALL HCHARd 0.6.1 28,53
>60 CALL HCHAR(4.1 3.1 28.6)
>70 CALL VCHAR(5.1 3.1 28.6]
>80 CALL VCHAR(5.1 8.1 28.63
>90 CALL HCHAR(7.14.1 28.43
>1 00 CALL HCHARC4.21 .1 28.53
>1 1 CALL VCHAR(5.23.1 28.63
2. RUN the program. (cat should appear on screen3
Note:
O You should draw the picture on the worksheet on page 163 first and use it as a guide
for drawing graphic characters with the TI-99/4A.
O Line 20 defines CHAR CODE 128 as a
Lines 30-50 draw the "C."
Lines 60-90 draw the "A."
Lines 100-110 draw the "T."
174
1 12,11
TAD Function
• Specifies tine starting position on the PRINT line for the next PRINT item.
• Operates much like a typewriter Tab key.
• Format: TAB (N) where N is a number in the range from 1 to 28.
• Example:
10 PRINT TAB (53; "TABBED 5"
Note:
O The PRINT line on the screen has 28 columns as compared to 32 columns
for the "graphics line."
O The TAB function always counts from Column 1 (the leftmost PRINT
position on the line) regardless of where and how many times it appears
in the PRINT statement.
O For best results, you should use a semicolon before and after a TAB
function if you have more than one TAB on a PRINT line.
175
12.12
TAD Example
YOUR ACTION
1. Type and enter the program shown.
2. RUN the program.
DISPLAY
>10CALL CLEAR
>20 PRINT TAB [5]:"STUDENrS";
TAB CIBrSTUDENTS"
>30 PRINT TAB (5):"NAME":TAB(1
8);"GRADE"
>35 PRINT
>40 PRINT TAB (5}:"ADRIENNE":T
AB (181:98
>45 PRINT
>50 PRINT TAB (5);"ALYCE":TAB(
183:100
STUDENT'S
NAME
STUDENTS
GRADE
ADRIENNE
ALYCE
98
100
DONE
Note:
O TAB function can be used to set up your results in a column format.
— All students' names would start printing at Column 5, TAB (5), and the students'
grades would start printing at Column 18. Notice that the numbers 98 and 100 are
actually printed in Column 19 because there is a space in front of a positive number.
176
SUMMARY
Grophics cind TAD
• CALL CHAR statement allows you to define your own special graphics
characters.
• CALL HCHAR displays a character anywhere on the screen and, optionally,
repeats it horizontally.
• CALL VCHAR also displays a character anywhere on the screen but,
optionally, repeats it vertically.
• TAB function specifies the starting position on the PRINT line for the next
PRINT item.
ASSIGNJVIENT 12-1
Those of you who would really like to learn more about graphics should read
the following pages in the TI-99/4A User's Reference Guide: pages II. 76 - 83
and III. 26 - 34. Also read Chapter 5, "Computer Graphics" (pages 96-127), in
Tl's Beginner's BASIC book.
PRACTICE 21
Graphics
■Using solid blocks (CHAR CODE="FFFFFFFFFFFFFFFF"), write a program that will do the
following:
1 . Draw an 8x8 square starting five blocks from the left of the screen and five blocks from the
top.
2. At the position ten blocks from the left side of the screen and ten blocks from the top, draw a
letter C that is 7 blocks long and 5 blocks wide.
3. Try other pictures or letters (if you have the time).
177
What You Will Learn
1. To explain the purpose of using arrays.
2. To set up one- and two-dimensional numeric arrays.
3. To explain the purpose and use of the terms DIM, A(3), A(2,3), DIM A(10),
DIM DB(7,5).
4. To develop, enter, and RUN programs using numeric arrays.
An Array
What is an array?
• An array is a lineup, an arrangement, or an orderly grouping of things.
Why use an array?
• We use it when we wish to have more variables available in a program.
— Although Tl BASIC permits the use of many variables for numerics,
sometimes thousands of variables are required for storing and retrieving
pieces of data.
— The array allows you to arrange your data so that it can be stored and
retrieved easily.
180
1 10,2
One-Dimensionol Array Illustration
SIX-ELEMENT ARRAY — NAMED A
SIX-ELEMENT ARRAY — NAMED B
A 1 2 3 4 5 6 -^Subscript q
Name
or label
A(3) is pronounced A SUB 3.
— A(3) represents the third cell
or box in the array (lineup).
— Data stored in this cell would be
addressed by the label A(3).
— Suppose data were stored in the
sixth cell: A(6)? (You got iti)
m
■a
Name
/
B(5)
\
Subscript
B(5) represents the fifth cell
in the array where data can be
stored and retrieved.
Note:
O A and B are optional names. Any valid variable name can be used to name an array
in Tl BASIC.
181
1 10.0
One-Dimensionol Array Program
YOUR ACTION
DISPLAY
1. Type in these program lines.
2. RUN the program.
>10 DATA 100.200.300.400.500.600
>20 FOR W=1 TO 6
>30 READ A(W)
>40 NEXT W
>50 FOR W=1 TO 6
>60 PRINT W.A(W)
>70 NEXT W
2
3
4
5
6
100
200
300
400
500
600
Note:
O Lines 20-40 store the data in array A(W).
O Lines 50-70 retrieve the data from array A(W) and PRINT the data.
182
H0>4
One-Dimensionol Array Program Analysis
ARRAY
CONTENTS
A(W)
A(1)— ^HM
A(2)-^f200l
A(3)— ^[300]
A(4)— ^300
A(5)-^[500]
A(6)— ^1600
• Above is an illustration of what happens after data are stored in array
A(W). Note that in location A(1), the first data element (100) is stored. In
location A(2), the second data element (200) is stored, and so on until the
sixth data element (600) is stored in location A(6). Remember that Line 10
of the program contained the data elements that were read using Lines 20
through 40.
183
10,5
Two-Dimensionol Array Illustration
COLUMN
ROW
J
1
4
1
2
3
4
c
5
D
1
11
12
13
14
15
16
2
21
22
23
24
25
26
3
31
32
33
34
35
36
4
41
42
43
44
45
46
5
51
52
53
54
55
56
6
61
62
63
64
65
66
36 ELEMENT ARRAY (MATRIX)
(NAMED H)
ROW
/
ARRAY
NAME
OR
LABEL
H(3;4)
REFERS TO CELL OR BOX ON ROW 3, COLUMN 4
COLUMN
184
EXEKCISE 10-1
Fill in the blanks using the matrix on page 184.
LABEL ROW COLUMN CONTENTS
H(1,1) _
H(4,5)
H(3,3)
H(2,3)
H(6,6)
H(1,6)
H(2,4)
H(4,4)
185
13.6
DIM Statement
• DIM
— Lets you set the depth (number of elements allowed per dimension).
— If no DIM statement is used, a depth of 11 (subscripts 0-10) is allowed
for each dimension of each array used.
— DIM statements may be placed anywhere in your program.
• Example:
10 DIM A(6),
B(2,3),
C(21)
Sets a one-dimensional
array A with 6 elements
A(0)— A(5) orA(l)— A(6)*
Sets a one-dimensional
array with 21 elements
A(0)— A(20) or A(1)— A(21)*
Sets a two-dimensional array B
with 3 rows (numbered 0-2)
and 4 columns (numbered 0-3)
*lf A(0) is not used.
186
1 10 J
Checkbook Arroy Example
• Consider the following table of checkbool< information:
Checl< #
Date Written
Amount
100
6/5/83
$ 15.50
101
6/7/83
25.00
102
6/15/83
145.00
103
6/22/83
65.00
104
6/30/83
211.00
105
6/30/83
79.50
• Note that every item in the table may be specified by reference to two
numbers: the row number and the column number. For example, Row 3,
Column 3 refers to the amount $145.00.
• The above table can be set up in a 6x3 array or matrix.
CK
1
2
3
1
100
60583
15.50
2
101
60783
25.00
3
102
61583
145.00
4
103
62283
65.00
5
104
63083
211.00
6
105
63083
79.50
Note:
O The date is recorded in the form mmddyy, where mm = month number, dd = day, and
yy = the last two digits of year.
O Since CK is a numeric array, alphanumeric characters such as dashes cannot
be stored.
187
lo.e
Checkbook Arroy Progrom
up the Arroy
YOUR ACTION
DISPLAY
1. Type in these lines:
2. Type RUN.
>5 CALL CLEAR
>10DIM CK(6.3]
>20 FOR R0\A/=1 TO 6
>30 FOR C0L=1 TO 3
>40 READ CKCROW.COL]
>50 NEXT COL
>55 NEXT ROW
>60 DATA 100.60583.15.50
>70 DATA 1 01 .60783.25.00
>80 DATA 102.61583.145.00
>90 DATA 103.62283.65.00
>1 00 DATA 1 04.63083.21 1 .00
>1 10 DATA 105.63083.79.50
>120 FOR R0W=1 TO 6
>130 SUM=SUM+CK(R0W.3)
>1 40 NEXT ROW
>1 50 PRINT "TOTAL OF CHECKS $":
>1 60 PRINT SUM
r
TOTAL OF CHECKS $ 541
Note:
O Line 10 sets up the dimension of the array. DIM CK(6,3) sets up an array with 6 rows
and 3 columns.
O Lines 20-55 read the values into array CK.
o Lines 60-110 contain the values of the array in DATA statements.
O Lines 120-140 add up all the checks written.
188
113.9
Checkbook Arroy Progrom
Monipuloting the Arroy
YOUR ACTION
DISPLAY
3. Do not type in NEW.
4. Add these steps to your program:
Type RUN.
(Enter 63083 for INPUT.)
Note:
O In Line 240 "<>" means "not equal to."
>200 INPUT "LIST CHECKS WRITT
EN ON [MM DD YY)":DT
>205 PRINT
>21 PRINT "CHECKS WRITTEN ON
";DT:"ARE LISTED BELOW:"
>215PRINT
>220 PRINT "CHECK #"."AMOUNr
>230 FOR R0W=1 TO 6
>240 IF CK(R0W.2]<>DT THEN 25
>245 PRINT CK(R0W.1}.CK(R0W.3
)
>250 NEXT ROW
TOTAL OF CHECKS $ 541
LIST CHECKS WRITTEN ON (MM D
□ YY3H
CHECKS WRITTEN ON 63083
ARE LISTED BELOW:
CHECK # AMOUNT
104 211
105 79.5
189
^ I ASSIGNMENT 13-1
Read pages 11.109 through 11.112 in the 7/ User's Reference Guide.
I SUiVUyiARY
Arrays
• A2 is not the same as A(2).
— A2 is an ordinary variable.
— A(2) is a subscripted variable.
• Any time you have a subscript larger than 10 (depth of 11), you must use
a DIM statement.
— Example:
10 DIMA (25), B(17, 18)
• One-Dimensional Array
^ Subscript
— A(3) is pronounced A SUB 3.
^ Name
• Two-Dimensional Array (Matrix)
^Row
— H(3,4) refers to cell or box on Row 3, Column 4.
Name "^Column
190
PRACTICE 22
Arrays
1 . Write a program to read the following numbers into an array and then PRINT them out:
676 150 175 188 190 277 876 976 912 544
2. Change the program to find the sum and average of the 10 numbers given.
3. Label the answer: THE SUM IS and THE AVERAGE IS
Hi PRACTICE 23
One-Dimensionol Array
1 . Suppose we had the following results of a quiz given to a class of 10 students:
Student # 1 23456789 10
Student's Grade 75 85 95 87 100 77 83 69 98 88
a. Using a one-dimensional array, write a program to find the class average.
b. Add the necessary program lines to find the highest grade and the lowest grade.
c. Have the program PRINT: GLASS AVERAGE IS HIGHEST GRADE IS _
and LOWEST GRADE IS
d. Enter the program and RUN it several times.
191
INT(X), ADS(XX and
RND Functions
What You Will Learn
1. To explain the purpose and use of INT(X), ABS(X), and RND functions.
2. To explain the purpose and use of the key word RANDOMIZE.
3. To write, RUN, and analyze programs using the INT(X), ABS(X), and
RND functions.
193
114.1
INT(X) Function
• INT(X), or integer function, allows you to round off any number, large or
small, positive or negative, into a whole number (or integer).
• INT(X) means
— If X is a positive number, then the largest whole number can be found
by chopping off the decimal part.
Example:
INT (5.7) = 5
INT (0.7) =
— If X is a negative number, the largest whole number can be found by
moving down to the next lowest whole number (that is, by making a
negative number more negative).
Example:
INT (-0.6) = -1 INT (-3.14) = -4
INT (-0.2) - -1 INT (-7.28) = -8
Note:
O The PRINT statement can be used for the above. For example.
PRINT INT (5.7), then press the lENTERI key.
194
EXERCISE 14-1
INT(X)
Graphic Representation
0-*(0.5)
-3-^(-2.5)
3-»(3.5)
-5-4 -3-2 -1 1 2 3 4 5
For negative numbers:
l\/love to next lowest
whole number
For positive numbers:
Chop off decimal part
0.5
-1.7
2.345
-0.8
3.1415
76.14
10.35
INT(X)
195
114,2
INT(X) Function — Kounding SS
YOUR ACTION DISPLAY
1. Type and enter this program.
2. Now RUN.
3. Add Line 15 to program as sliown.
4. Now RUN tlie program.
Note:
O In Line 15 we multiply by 100, add .5, tal<e the INT (which is now 667), and then
divide 667 by 100; 667/100 is 6.67, which is what we want — two decimal places.
>10A=20/3
>20 PRINT"$";A
r $ 6.BB6666667 ^
1 5 A =INT(1 00*A+.5)/1 00 ^
$ 6.67 ^
196
ASSIGNMENT 14-1
INT(X)
1 . Type NEW and enter this program for finding the area of a circle:
5 CALL CLEAR
1 REIVI AREA OF A CIRCLE
15 REM AREA=PI*RA2
20 INPUT "WHAT IS THE RADIUS?":R
30 PN3.14159
40 A=PI*RA2
50 PRINT "THE AREA IS";A
2. RUN the program several times to make sure it works.
3. Change the program to suppress (chop off) all of the numbers to the right
of the decimal point. (RUN the program to make sure it works.)
4. Change the program to make the answer accurate to one decimal place.
(For example, if R = 1, then Area (A) = 3.1.)
197
1 14.3 ~
ADS(X) Function
• ABS(X) = Abbreviation for absolute value of X
• Examples:
ABS (12) = 12 ABS (- 10) = 10
ABS(0) =0 ABS (-357) = 357
Note:
O ABS (25 - 10) = ABS (10 - 25) = 15
^ ASSIGNMENT 14-2
ADS(X)
YOUR ACTION
DISPLAY
1 . Type and enter the program shown.
2. RUN the program several times using
both positive and negative numbers.
>1 INPUT "TYPE ANY POSITIVE
OR NEGATIVE #":N
>20X = ABS(N]
>30 PRINT "N-.-X"
>40 PRINT N.X
Note:
O Regardless of the number you INPUT as N, the absolute value of X is the same number
v\/ithout the sign.
198
14.4
RND Function and RANDOMIZE Statement
• RND or random number function causes the computer to give you a
"surprise" number.
— It's as though the computer spins a wheel of chance.
— It's lil<e pulling a number out of a hat.
— It's unpredictable!
• RANDOMIZE is a complete program statement that "reseeds" the
random number generator.
— Each time you use RND the computer uses an internal seed number
to produce the desired random number. Therefore, it is a good idea
to set the seed number (reseed) to an unpredictable value in any
program that uses random numbers.
YOUR ACTION
DISPLAY
1. Type in these lines.
>5 RANDOMIZE
>10 PRINT RND
>20 GOTO 10
2. Type RUN.
(Screen should show many
random decimal numbers.)
(Press IFCTNI and ICLEARl to stop.)
Note:
O RND alone will produce numbers between and 1.
199
1 14.5
RND Function (Generating Integers)
• RND alone will produce a number between and 1.
• To generate integers between 1 and X, use the form
LET N=INT(X*RND)+1
Note:
O The general form for generating integer random numbers may seem complicated at
first; just remember that X is the highest random number you wish generated.
YOUR ACTION
DISPLAY
1 . Type NEW and enter these lines.
2. Type RUN.
3. Type RUN.
4. Change these lines.
5. RUN Several times. (Enter some
number between 5 and 100 at
the INPUT)
6. LIST the program.
>5 RANDOMIZE
>10X=20
>20 FOR N=1 TO 10
>30 PRINT INT (X*RND)-f 1:
>40 NEXT N
(Screen will show ten random
numbers between 1 and 20.)
(Screen will show another ten random
numbers between 1 and 20.)
>10 INPUT "VALUE FOR X":X
>20 FOR N=1 TO 50
1
(Screen will show fifty random
numbers between 1 and the number
you INPUT)
^-
5 RANDOMIZE
1 INPUT "VALUE FOR X?":X
20 FOR N=1 TO 50
30 PRINT INT(X*RNDH-1
40 NEXT N
200
^ I ASSIGNMENT 14-0
Coin Toss Program
1. Type in the following program:
5 CALL CLEAR
6 REM COIN TOSS PROGRAM
7 RANDOMIZE
10 REM T=TAILS. H=HEADS
15T=0
20 H=0
30 INPUT "HOW MANY TIMES SHALL I FLIP THE COIN?":N
40 CALL CLEAR
50 PRINT "I'M FLIPPING THE COIN... STAND BY"
60 FOR K=1 TO N
70 X=INT(2*RND)+1
80 IF X=1 THEN 100
90 H=H+1
95 GOTO 110
1 00 T=T+1
110 NEXT K
1 20 CALL CLEAR
130 PRINT "HEADS", "TAILS"
140 PRINT
145 PRINT KT
150 PRINT 100*H/N;"o/o".100*T/N;"%"
1 55 PRINT
1 60 PRINT "TOTAL FLIPS =":N
2. RUN this program several times and discuss the results.
Note:
O Lines 15 and 20 initialize the counters (H and T) to zero.
Line 60 begins the FOR-NEXT statement and executes "N" times.
Line 70 generates a random number (either a 1 or a 2).
In Line 90, "heads" are counted.
In Line 100, "tails" are counted.
Line 130 prints the headings.
Line 140 prints the values of H and T.
Line 150 calculates and prints the percentage of heads, percentage of tails.
Line 155 provides a space for better appearance.
201
ASSIGNMENT 14-4
Guess the Number Program
1. Type in the following program:
5 REM GUESS THE NUMBER GAME
10 RANDOMIZE
20 CALL CLEAR
30 X=INT(10*RND)+1
40 INPUT "GUESS A NUMBER BETWEEN 1 & 10:":N
50IFX=N THEN 110
60 IF X < N THEN 90
70 PRINT "HIGHER"
80 GOTO 40
90 PRINT "LOWER"
1 00 GOTO 40
110 PRINT "THAT'S RIGHT!"
120 FOR J=1 TO 2000
130 NEXT J
140 GOTO 10
2. RUN the program. (To stop the program, use the IFCTNI and I CLEAR
keys.)
3. Analyze the program.
Line 10 the random number generator.
Line 30 is the generator.
Line 40 allows the user to a number.
Lines 50 and 60 are statements that compare
(conditional, unconditional)
the random number with the INPUT number
X,N X,N
Lines 100, 70 and 90 are PRINT statements that guide the player.
Why does Line 140 GOTO Line 10, and why do Lines 80 and 100 GOTO
Line 40? Why were only two IF-THEN statements necessary to compare
the INPUT with the random number?
202
4. Modify (change) the program to pick a number between 1 and 100, and
RUN this program several times.
I SUMMARY
INT(X), ADS(X), RKD, RANDOMIZE
• INT(X) — Provides the Integer or whole-number value of X.
— If X is a positive number, it chops off the decimal part.
— If X is a negative number, it rounds it down to the next lowest
whole number (e.g., INT (—0.6) = —1).
• ABS(X) — Provides the absolute value of X (i.e., X is that same number
without the sign).
• RND — Causes the computer to give you a random number.
— INT (X * RND)+1 gives you a random number from 1 to
X inclusive.
• RANDOMIZE — A complete program statement that reseeds the random
number generator.
— It is used at the beginning of any program that uses random
numbers to ensure that the same sequence of random
numbers are not generated each time the program is RUN.
203
^ I PRACTICE 24
rNT(X)
1 . Fill in the blanks with the appropriate INT(X):
X INT(X)
0.7
-2.5
6.365
-0.8
-10.65
3.2425
-7.61
-0.3
0.3
2. The following program can be used for finding the area of a circle:
1 REM AREA OF A CIRCLE
15REM A=3.14159*RA2
20 INPUT "THE RADIUS IS": R
25 INPUT 'THE RADIUS IS IN [IN., FT. OR YD)": A$
30 A = 3.14159*RA2
40 PRINT "THE AREA IS"; A; "SQ. "; A$
a. Enter and RUN the program several times to make certain it works.
b. Change the program to suppress (chop off) all the numbers to the right of the decimal point
(RUN the program to make sure it works).
c. Change the program to make the answer accurate to one decimal place. (For example, if
R = 1,then area (A) = 3.1).
204
^ I PRACTICE 25
RANDOMIZE and RND
1 . Write a program that will let you pick a random number between 1 and 100. The program
should let you INPUT a number from the keyboard and provide the following clues on
your guess.
a. If the number you pick matches the number the computer picks, have the computer PRINT
"RIGHT ON."
b. If the number from the keyboard is too high, have the program print "LOWER."
c. If the number from the keyboard is too low, have the program print "HIGHER."
d. Enter the program and RUN it several times.
205
PART
Subroutines
What You Will Learn
1. To explain the purpose for using subroutines.
2. To explain the purpose and use of the key words GOSUB, RETURN,
ON-GOTO, ON-GOSUB.
3. To develop, enter, and RUN programs using subroutines.
/
207
1 15,1 ~
Subroutine
What Is It?
• A subroutine Is a short program or routine that is built into a large program
to do specific calculations or perform repetitive functions.
Why Use It?
• There are times when you need the same type of calculation at various
points in your program, but instead of retyping the statements needed for
this calculation each time, you can write a subroutine to perform the
needed calculations.
How Do You Call a Subroutine?
• To call or branch to a subroutine, use the GOSUB statement.
— The GOSUB XXXXX statement directs the computer to go to that line
number and execute the program steps until it reaches the key word
RETURN, which ends the subroutine.
— RETURN is always built into a subroutine and is used to tell the
computer that the subroutine is finished. When it is finished, the control
of the program is returned to the statement in the main program
immediately following the most recently executed GOSUB.
208
1 15,2
Subroutine Example
Main Program:
Subroutine:
10 REM GOSUB EXAMPLE
20
}
REST OF MAIN PROGRAM
90
1 00 GOSUB 3000
110 PRINT "BACK FROM SUBROUTINE": END
5
3000 PRINT "EXECUTING THE SUBROUTINE"
3010
}
REST OF SUBROUTINE
3040
I 3050 RETURN
209
\i5.Q
Subroutine lllustrotion
Main Program
Subroutines
10 REM MAIN PROGRAM BEGINS HERE
100 GOSUB1000
110 JEM MAIN PROGRAM CONTINUES
200 GOSUB 2000
210-REM MAIN PROGRAM CONTINUES
290 END REM MAIN PROGRAM ENDS
1000 REM SUBROUTINE #1
•
1060 RETURN
2000 REM SUBROUTINE #2
2050 RETURN
210
115,4
Analysis of Subroutine Illustration
1. When the computer reaches the GOSUB in Line 100, the program will
branch to Line 1000, which is the beginning of Subroutine #1.
2. After Subroutine #1 is executed and the RETURN (Line 1060) is reached,
control is passed back to the main program (Line 110). Note that Line 110
is the next higher number after the GOSUB that put it in the subroutine
(Line 100).
3. The computer continues through the main program to the GOSUB in
Line 200, which branches control to Subroutine #2 in Line 2000.
4. After the subroutine is executed, the RETURN (Line 2050) passes the
control back to Line 210 in the main program. (Note again that this is the
next higher line number after the GOSUB in Line 200.)
5. An END statement is included in the program (Line 290) after the main
program is finished to keep it from accidentally falling into the subroutine.
We want the subroutines to be executed only when we call for them by
a GOSUB.
211
115,5
Sample Program Using Subroutines
(Temperature Conversion)
Main
Program
10 REM TEMPERATURE CONVERSION PROGRAM
15 CALL CLEAR
20 INPUT "DO YOU WISH TO CONVERT C TO F (Y OR N)?":A$
25 PRINT
30 IF A$ = "Y" THEN 90
40 INPUT "DEGREES FAHRENHEIT ?":F
50 GOSUB 2000
55 PRINT
60 INPUT "HAVE YOU FINISHED (Y OR N)?":B$
70 IF B$ = "N" THEN 15
80 GOTO 120
90 INPUT "DEGREES CELSIUS ?":C
95 GOSUB 1000
100 GOTO 55
120 END
Subroutine
#1
1000 REM C TO F CONVERSION ROUTINE
1010F = (9/5)*C + 32
1015 PRINT
1020 PRINT C;"DEGREES C =";F;"DEGREES F"
1030 RETURN
Subroutine
#2
2000 REM F TO C CONVERSION ROUTINE
2010 C = (F-32)* (5/9)
2015 PRINT
2020 PRINT F; "DEGREES F =";C;"DEGREES C"
2030 RETURN
212
115,6
Analysis of Sample Program
Using Subroutines
1. Lines 10 through 120 comprise the main program.
2. Line 20 is an INPUT statement asl^ing the user if he wants to convert
from C to F. A yes answer ("Y") means the user wants to convert from
Celsius to Fahrenheit.
3. Line 30 tests the answer to the INPUT and branches either to Line 90 or
to Line 40.
4. Line 40 allows the user to INPUT the degrees Fahrenheit.
5. Line 50 branches to the subroutine on converting F to C (Line 2000).
6. Line 60 asks the user if he is finished. If the user answers "N" then the
program will clear the screen (Line 15) and start the main program over
again. If the user answers "Y" then the program will end (Line 120).
7. Line 90 is similar to Line 40. It allows the user to INPUT the degrees
Celsius.
8. Line 95 branches to the subroutine on converting C to F (Line 1000).
9. Line 100 routes the program to Line 55 where a line feed is executed for
better output appearance and the user is asked if he is finished.
10. Line 1000 through Line 1030 contain the subroutine for converting
Celsius to Fahrenheit and PRINTing the answer. Line 1030 RETURNS
control to Line 100 in the main program.
11. Line 2000 through Line 2030 contain the subroutine for converting
Fahrenheit to Celsius and PRINTing the answer. Line 2030 RETURNS
control to Line 55 in the main program.
213
115,7
Subroutine Exercise
10 PRINT "THIS IS";" ";
20 GOSUB 1000
30 PRINT "OF HOW";" ";
40 GOSUB 2000
50 PRINT "WORKS"
60 END
1000 PRINT "AN EXAMPLE";" ";
1 01 RETURN
2000 PRINT "A SUBROUTINE";" ";
2010 RETURN
1. Analyze the program and write the message
2. Now type and enter the program.
3. RUN the program. Does it agree with your message?
214
ASSIGNMENT 15-1
Analyze the program below and write the message:
10 LETS = 10
20 GOSUB 2000
30 B = B + 5
40 GOSUB 2000
50B = B + 10
60 GOSUB 2000
99 END
2000 REM SUBROUTINE
2010 IF B< 12 THEN 2045
2020 IF B = 25 THEN 2070
2030 PRINT "PRIME"
2040 GOTO 2080
2045 CALL CLEAR
2050 PRINT "LEEDS"
2060 GOTO 2080
2070 PRINT "COMPUTERS"
2080 RETURN
Message
215
1 15.6
Conditional Branching (The Long Way!)
YOUR ACTION
1 . Type NEW and enter this program.
2. Before you RUN the program, analyze
it. Can you predict what will happen
when you RUN it? (I sure hope you
can by now!)
3. RUN the program several times until
you feel comfortable with it.
DISPLAY
>5 CALL CLEAR
>10 INPUT 'TYPE A NUMBER FROM 1 TO 3":N
>20 IFN = 1 THEN 110
>30 IFN = 2THEN 130
>40 IFN = 3THEN 150
>50 PRINT "HEY. I WANT A NUMBER FROM 1 TO 31"
>60 GOTO 10
>1 10 PRINT "N = 1"
>120 END
>130 PRINT "N = 2"
>140END
>150 PRINT "N = 3"
>160 END
216
1 15.9
Conditionol Dronching (The Short Woy)
ON-GOTO
YOUR ACTION DISPLAY
4. Erase Lines 20, 30, and 40. Sim ply type
in each line number and press lENTER
5. Type this line:
6. LIST your program,
(If your program does not look like
this, fix it!)
7. RUN the program with the
following INPUTs:
1.5
1.8
1.2
.8
2.6
3.99
.4
0:
>20 ON N GOTO 110.130.150
5 CALL CLEAR
10 INPUT 'TYPE A NUMBER FROM
1 TO 3 ":N
20 ON N GOTO 110.130.150
50 PRINT "HEY. I WANT A NUMB
ER FROM 1 TO 3!"
60 GOTO 10
110 PRINT "N = 1"
120 END
130 PRINT "N = 2"
140 END
150 PRINT "N = 3"
160 END
N = 2
N = 2
N = 1
N = 1
N = 3
• BAD VALUE IN 20
• BAD VALUE IN 20
Note:
O The ON-GOTO statement rounds the value of the INPUT. If the rounded value of the
INPUT is less than 1 or greater than the number of line numbers listed (in this case, 3),
the program will stop running and you will get the error message shown. You should
anticipate this and use IF-THEN statements to check the INPUT value whenever you
plan on using ON-GOTO.
217
ASSIGNMENT 15-2
1. Type and enter the following program:
5 CALL CLEAR
10 INPUT "ENTER A NUMBER FROM 1 TO 5: ":N
20 IFN<>INT(N)THEN 10
30IFN<1 THEN 10
40 IFN>5THEN 10
50 ON N GOTO 1 00.1 1 0.1 20.1 30.1 40
100 PRINT "N = 1"
105 GOTO 10
110 PRINT "N = 2"
115 GOTO 10
120 PRINT "N = 3"
125 GOTO 10
130 PRINT "N = 4"
135 GOTO 10
140 PRINT "N = 5"
145 GOTO 10
Note:
O Line 20 checks to see if the INPUT was an integer. If N does not equal the
integer of itself, then the program swings back to the INPUT for another
value.
O Line 30 checks if N is less than 1. This is to make sure an error message
does not occur.
O Line 40 checks if N is greater than 5, also turning control back to Line 10 if
it is, thus avoiding the error message.
2. RUN the program several times and record the following:
INPUT OUTPUT
218
1 15.10
ON-GOSUD
• Has the form
ON n GOSUB XXXX.YYYY.ZZZZ,...
where n is a constant, a variable, or a variable expression.
• Works similarly to ON-GOTO except control branches to one of the
subroutines specified by the line numbers in the line number list.
• If the value of n is less than 1 or greater than the number of line numbers in
the list, an error message will occur.
• After one of the subroutines has been executed and a RETURN is
encountered, control passes to the line following the ON-GOSUB statement.
219
^ I ASSIGNMENT 15-0
1. Type in the following program:
5 RANDOMIZE
10 CALL CLEAR
20 PRINT "THIS PROGRAM GIVES A QUIZ."
30 PRINT "YOU HAVE A CHOICE:"
40 PRINT "1. ADD"."2. SUBTRACT"
50 PRINT "3. MULTIPLY"."4. DIVIDE"
60 INPUT "WHAT IS YOUR CHOICE? ":N
70 IF N <> INT(N) THEN 30
80 IF N < 1 THEN 30
90 IFN>4THEN 30
100A=INT(10*RND)+1
110B=INT(10*RND)+1
1 20 ON N GOSUB 500.600.700.800
1 30 INPUT "YOUR ANSWER? ":S
140 IFS=A1 THEN 180
1 50 PRINT "NO. THE ANSWER WAS"; A1
160 INPUT "ANOTHER PROBLEM? ":A$
1 70 IF A$="YES" THEN 1
1 75 END
1 80 PRINT "VERY GOOD!"
1 90 GOTO 1 60
500 A1=A+B
510 PRINT A:"+";B;" = "
520 RETURN
600A1=A-B
610 PRINT A:"-";B:" = "
620 RETURN
700A1=A*B
710 PRINT A;"*";B;" = "
720 RETURN
800A1=A/B
810 PRINT A;"/":B;" = "
820 RETURN
220
2. Change the program so that:
• the problems generate larger numbers.
• the answer to the subtraction problem is never negative.
• the answer to the division problem is always an integer.
• the person always gets 5 problems at a time.
• the person receives a score of the number of correct answers.
I SUMMARY
GOSUD, ON-GOSUD, 0N-60T0
• GOSUB XXXX
— Here the computer branches to the subroutine beginning at XXXX
(the specified line number).
— The subroutine is executed until a RETURN statement is encountered.
— Program control returns to the statement that follows the GOSUB
statement in the main program.
• ON n GOSUB XXXX, ,YYYY
— This is a conditional branching statement that sends control of the
program to one of the subroutines specified in the line number list
(XXXX, ,YYYY).
— The value of the test variable (n) determines which subroutine is exe-
cuted. For example, if n=1, control is passed to the subroutine in
line XXXX.
— Once a subroutine is being executed, the rules governing GOSUB are
followed, i.e., a RETURN passes control to the statement following the
ON n GOSUB.
221
• ON n GOTO XXXX, ,YYYY
— This statement works similar to ON n GOSUB except control does not
pass to a subroutine but to another part of the main program.
— The value of n determines which line number is executed next.
Note:
O n can be a constant, a variable, or a variable expression.
O n must not be less than 1 or greater than the number of line numbers in
the line number list or an error message will occur.
PKACTICE 26
Program to Convert
Fahrenheit and Vice Verso
to
1 . Write a program that will do the following:
a. Convert Celsius to Fahrenheit.
b. Convert Fahrenheit to Celsius.
0. Allow you to select either A or B above.
d. Allow you to INPUT from keyboard.
e. PRINT the answer as follows:
* DEGREES CELSIUS = !^
or
DEGREES FAHRENHEIT =
DEGREES FAHRENHEIT
DEGREES CELSIUS
* Keyboard INPUT value
** Calculated output value
222
PRACTICE 27
Program for Sample Profit/Loss Statement
1 . When a product is sold for more than it costs, the seller receives a profit. When a product is
sold for less than it costs, the seller takes a loss.
Therefore: sell price — cost = profit or loss
If we let: S = Sell price
C = Cost
U = No. of units
P = Profit
L = Loss
Then: P (or L) = S*U - C*U
a. Write a program that will compute the profit or loss for a business if the sell price and cost
are known. (Note: Program should permit you to enter cost and sell price from the
keyboard.)
b. Have the computer PRINT the following:
NO. OF UNITS
UNIT PRICE ($)
UNIT COST ($)
TOTAL SALES ($)
TOTAL COST ($)
PROFIT/ LOSS ($)
% OF SALES
c. RUN the program several times and record your answer.
223
^1 EXTRA PRACTICE 1
Programming Mothemoticol Operators
1 . Given two numbers A=25 and B=5:
a. Write one program that will add, subtract, divide (A/B), multiply, and square the two
numbers (A and B).
b. The answer should PRINT as shown here:
THE SUM OF A AND B IS (your answer).
THE DIFFERENCE BETWEEN A AND B IS (your answer).
THE QUOTIENT OF A AND B IS (your answer).
THE PRODUCT OF A AND B IS (your answer).
THE SQUARE OF A IS (your answer).
THE SQUARE OF B IS (your answer).
^1 EXTRA PRACTICE 2
the Average
1 . Write a program to find the average of three numbers.
2. Have the program PRINT: THE AVERAGE IS
3. Add a program line to have the program PRINT the average of your # , your.#
and your # is (your answer). Example: THE AVERAGE OF 3, 4, AND 8 IS 5.
^1 EXTRA PRACTICE
More Mothemotical Operotions
Write five separate programs to PRINT the answer to these problems (the answer should read
25 * 2 + 4 = 54, and so on.):
1. 25*2+4
2. 3A2+4-2
3. 36/4*5
4. 28+4*6/8
5. (18-2)/3+4(6*3)+2A3
224
^|EXTRAPRACTICE4
Print Zones
Part I.
Write a program to PRINT the word "LEEDS" in the following ways:
Z0NE1
ZONE 2
1. LEEDS
LEEDS
2. LEEDS
3.
LEEDS
Part II.
Using page 76, type in the information as shown (LEEDSPRIME)...and so on.
1 . Count the number of characters in the two zones. How many?
2. How many in Zone 1 ; Zone 2 ?
EXTRA PRACTICE 5
Area of Square and Volume of Cube
1 . Write a program to solve the following problems. Label your answers.
a. The side of a square is 27 inches. Find its area (area (A) = s^).
b. If the side of a cube is also 27 inches, find its volume (volume (V) = s^).
2. Using INPUT statements, write a program to find the area of a square and volume of a cube.
a. Solve the problems above (assume sides of a square and cube are equal).
b. Using different lengths for the side, RUN the program again (assume that the sides of the
square and the cube are equal).
225
^ I EXTRA PRACTICE 6
Printing Tobies of Numbers,
Squares, ond Cubes
1. Write a program to generate the first 25 numbers and PRINT their squares on the same line.
Example: 1 1
2 4
3 9
4 16
and so forth
2. Write a program to generate the first 25 numbers and PRINT their cubes on the same line.
Example: 1 1
2 8
3 27
4 64
and so forth
3. Write a program to generate all the numbers from 20 to 1 and PRINT the numbers, and their
squares and cubes, on the same line and in four columns.
Example: 20 400 8000 160000
19 361 6859 130321
18 324 5832 104976
and so forth
EXTRA PRACTICE 7
Printing Three-Times ond
Nine-Times Tables
1 . Write a program to generate the three-times table from 3 X 1 = 3 to 3 X 12 = 36. The printout
should look exactly like this:
3*1=3
3*2 = 6
3*3 = 9
3*4 = 12
and so forth
2. Write a program to generate the nine-times table from 9X1 = 9 to 9X12 = 108.
226
^1 EXTRA PRACTICE 6
Two-Di
Array
1 . Suppose we have a class of ten students. The course grade is based upon three quizzes,
and the results for the class are as follows:
student #
1
2
3
4
5
6
7
8
9
10
Quiz #
1
88
41
100
88
79
76
86
90
85
100
2
75
52
65
57
98
86
96
91
86
92
3
71
47
75
77
86
96
85
92
97
82
a. Write a program to PRINT the following information:
Student #
1
2
3
4
and so forth
Quiz ft
1
2
3
Course Avg./ Student
?
?
?
Course Avg./ Quiz
9
2
9
Computer to calculate
and PRINT average
Computer to calculate
and PRINT average
227
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